ISO/FDIS 4223-1

• Abstract:

  ISO 4223-1:2017 defines a number of significant terms related to pneumatic tyres used in the tyre industry, together with corresponding codes, symbols and values. NOTE 1 For other terms used in this field and their equivalents in other languages, see ISO 3877 (all parts). For terms and definitions relating to wheels/rims, see ISO 3911. NOTE 2 Annex A forms a normative part of this document.

• Status: Not Published
• ICS: 01.040.83 - Rubber and plastics industries (Vocabularies)
• ICS: 83.160.01 - Tyres in general
• Technical Committee: ISO/TC 31 - Tyres, rims and valves
• Drafting Committee: ISO/TC 31 - Tyres, rims and valves
• Current Stage: 5020 - FDIS ballot initiated: 2 months. Proof sent to secretariat
• Start Date: 30-Jul-2026
• Completion Date: 30-Jul-2026

• Revises: ISO 4223-1:2017 - Definitions of some terms used in the tyre industry — Part 1: Pneumatic tyres
• Effective Date: 24-Jun-2023

Overview

ISO/FDIS 4223-1:2025, titled Tyre industry - Vocabulary - Part 1: Pneumatic tyres, is an international standard developed by ISO Technical Committee 31. The document focuses on the harmonization of terminology related to pneumatic tyres, which are tyres designed to contain gas at adjustable pressures. This standard provides clear definitions, codes, symbols, and values for terms widely used throughout the tyre industry, contributing to consistent communication among manufacturers, regulators, and users.

Key Topics

Terminology and Definitions

• Comprehensive definitions for tyres used in different applications including normal, special use, snow, ice grip, and temporary-use spare tyres
• Classification of tyres by structure, such as diagonal, bias-belted, and radial construction
• Categories for service description, including load index and speed symbol
• Identification of main tyre components: tread, sidewall, bead, cord, ply, inner liner, and more

Designation, Codes, and Markings

• Standard tyre size designations that specify nominal section width, aspect ratio, structure type, and rim diameter
• Codes for specific tyre applications: e.g., P for passenger car, LT for light truck, NHS for not for highway service, and others
• Detailed explanations for symbols and additional markings used in the tyre industry

Tyre Dimensions and Testing Terms

• Definitions and guidelines for measuring section width, overall width, aspect ratios, maximum diameters, and rim diameters
• Terms used in tyre performance and durability testing, including bead separation, rolling resistance, grip index, and abrasion level

Applications

The ISO/FDIS 4223-1 standard holds significant practical value for several stakeholders in the tyre industry and related fields:

• Tyre manufacturers: Ensures accurate labelling, quality assurance, and compliance with international terminology, aiding in global trade and market access.
• Regulatory bodies: Facilitates the implementation of safety and performance regulations by referencing unified definitions and measurement symbols.
• Vehicle manufacturers and OEMs: Supports correct tyre selection, specification, and communication regarding performance and compatibility.
• Retailers, distributors, and service providers: Assists with customer information, inventory management, and correct fitment based on standardized markings.
• Testing Laboratories: Standardizes testing procedures by providing universally accepted definitions for terms like load index, speed category, and rolling resistance.

Adoption of ISO/FDIS 4223-1 reduces ambiguity and errors related to tyre designations, enhancing overall safety and efficiency in the automotive sector.

Related Standards

Numerous ISO standards complement ISO/FDIS 4223-1 within the pneumatic tyre and wheel segment:

• ISO 3877 (all parts): Vocabulary for tyres, rims, and valves in multiple languages, further enhancing international compatibility.
• ISO 3911: Definitions and designations for wheels and rims suitable for pneumatic tyres.
• ISO 16992: Details on spare unit substitutive equipment for passenger car tyres.
• ISO 18106: Methods for testing snow grip performance of passenger car, commercial vehicle, truck, and bus tyres.
• ISO 18805: Classification of tyres for agricultural, forestry, and construction machines.
• ISO 19447: Ice grip performance testing for passenger car tyres.

Together, these standards provide a robust framework for terminological clarity, safety, and performance in the tyre and automotive industries.

Keywords: ISO tyre standard, pneumatic tyre terminology, tyre codes, tyre industry, tyre size designation, tyre testing, ISO/FDIS 4223-1, international tyre standards, tyre labelling.

FINAL DRAFT
International
Standard
ISO/TC 31
Tyre industry — Vocabulary —
Secretariat: ANSI
Part 1:
Voting begins on:
2026-07-30
Pneumatic tyres
Voting terminates on:
2026-09-24
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
Reference number
FINAL DRAFT
International
Standard
ISO/TC 31
Tyre industry — Vocabulary —
Secretariat: ANSI
Part 1:
Voting begins on:
Pneumatic tyres
Voting terminates on:
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
© ISO 2026
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
or ISO’s member body in the country of the requester.
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland Reference number
ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and symbols . 1
3.1 Terms relating to category of use .1
3.2 Terms relating to service description .3
3.3 Terms relating to structure .4
3.4 Terms relating to main components .5
3.5 Terms relating to dimensions (see Figure 3) .6
3.6 Terms, definitions and symbols of designation .8
3.7 Terms relating to tyre testing .11
3.8 Other general terms and definitions . 13
Annex A (normative) Loads, speeds and rim diameters .16
Bibliography .28

iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 31, Tyres, rims and valves.
This sixth edition cancels and replaces the fifth edition (ISO 4223-1:2017), which has been technically
revised.
The main changes are as follows:
— inclusion of terms that are new to the tyre industry;
— revision of references.
A list of all parts in the ISO 4223 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

iv
FINAL DRAFT International Standard ISO/FDIS 4223-1:2026(en)
Tyre industry — Vocabulary —
Part 1:
Pneumatic tyres
1 Scope
This document defines terms related to pneumatic tyres, i. e. tyres suitable for containing a gas at a pressure
which can be adjusted.
This document specifies the corresponding codes, symbols and values for these tyres.
NOTE For other terms used in this field and their equivalents in other languages, see ISO 3877 (all parts). For
terms and definitions relating to wheels and rims, see ISO 3911.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 3911, Wheels and rims for pneumatic tyres — Vocabulary, designation and marking
ISO 16992, Passenger car tyres — Spare unit substitutive equipment (SUSE)
ISO 18805, Tyre classification — Agricultural, forestry and construction machines
ISO 19447, Passenger car tyres — Method for measuring ice grip performance — Loaded new tyres
3 Terms, definitions and symbols
For the purposes of this document, the terms, definitions and symbols given in ISO 3911 and ISO 18805 and
the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at https:// www .electropedia .org/
— ISO Online browsing platform: available at https:// www .iso .org/ obp
3.1 Terms relating to category of use
3.1.1
normal tyre
tyre intended for use on public streets, roads and highways and that are not marked with “M+S” (or other
variations) or severe snow or special usetyre (3.1.2) designations

3.1.2
special use tyre
tyre intended for mixed use both on- and off-road or for other special duty and primarily designed to initiate
and control vehicle motion in off-road conditions
Note 1 to entry: Examples of special use tyre designations are ET (3.6.1.1.29), MPT (3.6.1.1.30), ML (3.6.1.1.16), and
POR (3.6.1.1.31).
3.1.2.1
professional off-road tyre
POR tyre
special usetyre (3.1.2) primarily used for service in severe off-road conditions
3.1.3
snow tyre
mud and snow tyre
tyre whose tread (3.4.4) pattern, tread compound or structure (3.3.1) is primarily designed to achieve in
winter conditions (e.g. either on snow or on mud and sand, or both) a performance better than that of a
normal tyre (3.1.1) with regard to its ability to initiate or control vehicle motion
Note 1 to entry: It is identified by a combination of the letters “M” and “S”, e. g. M+S, M&S, M.S.
3.1.3.1
ice grip tyre
passenger car snow tyre (3.1.3) that is classified as a severe snow use tyre (3.1.4) and additionally designed to
be used on road surfaces covered with ice
Note 1 to entry: An ice grip tyre shall conform to ISO 19447.
[3]
Note 2 to entry: An ice grip tyre that conforms to UN Regulation No. 117 shall be marked with the ice grip symbol
(see Figure 1):
Figure 1 — Ice grip symbol (ISO 7000-3964)
3.1.4
severe snow use tyre
tyre for use in severe snow conditions
tyre whose tread (3.4.4) pattern, tread compound or structure (3.3.1) is specifically designed based on
performance testing using ISO 18106 and which is identified by an “Alpine” or “3 Peak Mountain Snow Flake
(3PMSF)” symbol
Note 1 to entry: Regional standards and regulatory requirements can apply for dimensions and performance criteria
for severe snow use tyres as well as for the placement of the 3 peak mountain snow flake (3PMSF) symbol (see
Figure 2).
Figure 2 — 3 peak mountain snow flake (3PMSF) symbol
3.1.5
temporary-use spare tyre
tyre different from a tyre intended to be fitted to any vehicle for normal driving conditions but intended
only for temporary use under restricted driving conditions
3.1.5.1
T-type temporary-use spare tyre
temporary-use spare tyre (3.1.5) designed for use at an inflation pressure higher than those established for
standard and reinforced tyres (3.8.11)
Note 1 to entry: It is designated with the “T” prefix.
3.1.6
not for highway service tyre
NHS tyre
tyre primarily designed for use outside of public roads, but suitable for temporary or incidental use on public
roads and identified with the letters “NHS” (3.6.1.1.8)
EXAMPLE Earth-mover, industrial, agricultural equipment and motorcycles tyres can be not for highway service
tyres.
Note 1 to entry: Motorcycle tyres that are marked with “NHS” shall not be used on public roads.
3.1.7
traction tyre
tyre intended to be fitted primarily to the drive axle(s) of a vehicle to maximize force
transmission in various circumstances
Note 1 to entry: Traction tyres can be marked with “TRACTION”.
3.2 Terms relating to service description
3.2.1
service description
tyre identification, in addition to the tyre size designation (3.6.1), which consists of one or two load indices
(LI) (3.2.1.1) and a speed symbol (SS) (3.2.1.2)
Note 1 to entry: When two load indices are used, these indicate the load carrying capacity in single and dual fitment.
EXAMPLE 91H or 121/119S.
3.2.1.1
load index
LI
numerical code which indicates a reference load used to define the load carrying capacity of the tyre, which
can depend on operating conditions and tyre type
Note 1 to entry: The standardized load indices and the assigned reference loads are specified in Table A.1.

3.2.1.2
speed symbol
SS
alpha or alpha-numeric code which indicates the speed category (3.2.1.3) of the tyre, which can depend on
operating conditions and tyre type
Note 1 to entry: The standardized speed symbols are specified in Table A.2.
3.2.1.3
speed category
maximum speed which the tyre can sustain, expressed by the speed symbol, and which is part of the service
description (3.2.1)
Note 1 to entry: The speed categories assigned to the standardized speed symbols are specified in Table A.2.
3.2.1.4
additional service description
secondary service description identifying a special type of service at which the tyre is allowed to operate in
addition to the main service description
Note 1 to entry: The additional service description shall be marked within a circle and shall be located close to the
main service description.
Note 2 to entry: The additional service description shall consist of either one or two load indices that are greater than,
and a speed symbol that indicates a speed category that is less than, that of the main service description or one or two
load indices that are lower than or equal to and a speed symbol that indicates a speed category that is greater than
that of the main service description.
3.3 Terms relating to structure
3.3.1
structure
technical characteristics of the tyre’s structure
3.3.1.1
diagonal structure
bias-ply structure
cross-ply structure
structure (3.3.1) in which the ply cords (3.4.5) that extend to the beads (3.4.1) are laid at alternate angles of
substantially less than 90° to the centreline of the tread (3.4.4)
3.3.1.1.1
diagonal tyre
tyre having a diagonal structure (3.3.1.1)
3.3.1.2
bias-belted structure
structure (3.3.1) in which the ply cords (3.4.5) that extend to the beads (3.4.1) are laid at alternate angles
of substantially less than 90° to the centreline of the tread (3.4.4) and are restricted by a belt (3.4.10)
comprising one or more layers of substantially inextensible cord (3.4.5) material
3.3.1.2.1
bias-belted tyre
tyre having a bias-belted structure (3.3.1.2)
3.3.1.3
radial structure
structure (3.3.1) in which the ply cords (3.4.5) that extend to the beads (3.4.1) are laid at substantially 90° to
the centreline of the tread (3.4.4) in a zone including most of the sidewall (3.4.2) and located outside the bead
(3.4.1) and the essentially inextensible circumferential belt (3.4.10) that stabilizes the carcass (3.4.8)

3.3.1.3.1
radial tyre
tyre having a radial structure (3.3.1.3)
3.3.1.3.2
extended radial structure
radial structure (3.3.1.3) in which the ply cords (3.4.5) that extend to the beads (3.4.1) are not laid
substantially at 90° to the centre line of the tread (3.4.4) across the complete cross section of the tyre
3.4 Terms relating to main components
3.4.1
bead
part of the tyre shaped to fit the rim (3.7.12) and having a core made of one or several essentially inextensible
strands with the plies (3.4.6) wrapped around the core
3.4.2
sidewall
portion of the tyre between the tread (3.4.4) and the bead (3.4.1)
3.4.3
sidewall rubber
rubber layer on the sidewall (3.4.2) of the tyre and over the carcass (3.4.8), which can include ornamental or
protective ribs, tyre labelling and markings, and moulded fitting lines
3.4.3.1
rim protector
feature incorporated into the lowersidewall (3.4.11) area of the tyre which is intended to protect the rim
(3.7.12) flange from damage
3.4.4
tread
part of a tyre which comes into contact with the ground
3.4.5
cord
textile or non-textile strands (threads) used in various components of the tyre carcass (3.4.8)
EXAMPLE Plies (3.4.6), belts (3.4.10), breakers (3.4.9).
3.4.6
ply
layer of rubber-coated parallel cords (3.4.5)
3.4.7
inner liner
layer of rubber on the inside of the carcass (3.4.8) used especially in tubeless tyres to minimize air loss
3.4.8
carcass
part of a tyre other than the tread (3.4.4) and the sidewall rubber (3.4.3) which, when inflated, bears the load
3.4.9
breaker
intermediate ply (3.4.6) not extending to the bead (3.4.1)
3.4.10
belt
bracing ply
layer of material underneath the tread (3.4.4), laid substantially in the direction of the tread centreline, that
restricts the carcass (3.4.8) circumferentially

3.4.11
lower sidewall
area below the line of maximum section width (3.5.1) of the tyre, visible when the tyre, fitted to a rim (3.7.12),
is viewed from the side
3.4.12
tread groove
space between the adjacent ribs or blocks in the tread (3.4.4) pattern
3.4.13
tread wear indicator
projection within the tread grooves (3.4.12) designed to give a visual indication of the degree of wear of the
tread (3.4.4)
3.4.14
chafer
material in the bead (3.4.1) area to protect the carcass (3.4.8) against rim (3.7.12) chafing
3.5 Terms relating to dimensions (see Figure 3)

a
Specified rim width.
Figure 3 — Dimensions
3.5.1
section width
S
linear distance between the outside of the sidewalls (3.4.2) of an inflated pneumatic tyre, when fitted on a
measuring rim (3.7.10), excluding elevations due to labelling (markings), decorations, protective bands or
ribs, or rim protector (3.4.3.1)
3.5.2
overall width
W
linear distance between the outsides of the sidewalls (3.4.2) of an inflated pneumatic tyre, when fitted on a
measuring rim (3.7.10), including labelling (marking), decoration, protective bands or ribs, and rim protector
(3.4.3.1), and in the case of tyres where the tread (3.4.4) is wider than the section width (3.5.1), the overall
width corresponds to the tread width

3.5.3
maximum overall tyre width in service
overall width (3.5.2) plus
a) manufacturing tolerances; and
b) tolerance for service growth
3.5.4
section height
H
half the difference between the overall diameter (3.5.5) and the nominal rim diameter (3.5.9)
3.5.5
overall diameter
D
o
diameter of an inflated pneumatic tyre, when fitted on a measuring rim (3.7.10), at the outermost surface of
the tread (3.4.4), applying to new tyres (3.8.3) or newly retreaded tyres (3.8.9)
3.5.6
static maximum overall tyre diameter in service
D
os
overall diameter (3.5.5) plus
a) manufacturing tolerances; and
b) tolerance for service growth
3.5.7
dynamic maximum overall tyre diameter in service
D
od
overall diameter (3.5.5) plus
a) manufacturing tolerances;
b) tolerance for service growth; and
c) allowance for dimensional changes due to centrifugal force
Note 1 to entry: This definition applies only to motorcycle tyres; the allowance in 3.5.7 c) shall be taken into account
when designing for tyre clearances.
3.5.8
nominal aspect ratio
H/S
ratio of the tyre [on its theoretical rim (3.7.12)] nominal section height (3.5.4) to the nominalsection width
(3.5.10) multiplied by 100
3.5.9
nominal rim diameter
D
r
conventional number corresponding to the diameter of the rim (3.7.12) expressed either as a size code
(number less than 100) or in millimetres (number greater than 100), but not as both
Note 1 to entry: See Table A.3 for the nominal rim diameters, expressed in millimetres, that shall apply to nominal rim
diameters expressed by codes.
3.5.10
nominal section width
S
N
section width (3.5.1) indicated in the tyre size designation (3.6.1), and used for calculation of tyre dimensions
Note 1 to entry: Regional tyre standards have used “SN”.

3.5.11
specified rim diameter
diameter of the intersection of the axial projections of the bead seat and the flange of a rim (3.7.12)
Note 1 to entry: The specified rim diameters recommended to be used for nominal rim diameters (3.5.9) expressed by
codes are specified in Table A.4.
Note 2 to entry: Bead seat and flange are defined in ISO 3911.
3.6 Terms, definitions and symbols of designation
3.6.1
tyre size designation
designation showing:
— the nominalsection width (3.5.10);
— the nominal aspect ratio (3.5.8);
— indication of the structure (3.3.1) placed in front of the nominal rim diameter (3.5.9) marking, as follows:
— for diagonal tyres (3.3.1.1.1): the symbol “-” or the letter “D”;
— for bias-belted tyres (3.3.1.2.1): the letter “B”;
— for radial tyres (3.3.1.3.1): the letter “R”;
— for run flat tyre
...

ISO/DISFDIS 4223-1:2025(en)
ISO/TC 31
Secretariat: ANSI
Date:2025-10-08 2026-07-15
Tyre industry — Vocabulary, Designations and Markings — —
Part 1:
Pneumatic tyres
Industrie du pneumatique — Vocabulaire, désignations et marquages — Partie 1: Pneumatiques

FDIS stage
ISO 4223-1
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication
may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying,
or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO
at the address below or ISO'sISO’s member body in the country of the requester.
ISO Copyright Officecopyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: + 41 22 749 01 11
Email:
E-mail: [e-mail]
Website: www.iso.org
Published in Switzerland.
ii © ISO 2017 – All rights reserved

ISO/DIS 4223-1:2025(en)
Contents
Foreword . iv
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and symbols . 1
3.1 Terms relating to category of use . 2
3.2 Terms relating to service description . 4
3.3 Terms relating to structure . 5
3.4 Terms relating to main components . 5
3.5 Terms relating to dimensions (see Figure 3) . 7
3.6 Terms, definitions and symbols of designation . 9
3.7 Terms relating to tyre testing . 13
3.8 Other general terms and definitions . 15
Annex A (normative) Loads, speeds and rim diameters . 18
Bibliography . 1

iii
ISO 4223-1
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types of
ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights
in respect thereof. As of the date of publication of this document, ISO had not received notice of (a) patent(s)
which may be required to implement this document. However, implementers are cautioned that this may not
represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
.
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html
This document was prepared by Technical Committee ISO/TC 31, Tyres, rims and valves.
This sixth edition cancels and replaces the fifth edition (ISO 4223--1:2017), which has been technically
revised.
The main changes are as follows:
— — inclusion of additional terms and definitions that are new and commonly used in to the tyre industry;
— editorial changes to enhance comprehensibility of the text
— — updaterevision of references.
A list of all parts in the ISO 4223 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
.
complete listing of these bodies can be found at www.iso.org/members.html

iv © ISO 2017 – All rights reserved

ISO/DISFDIS 4223-1:20252026(en)
Definitions of some terms used in the tyre
v
DRAFT International Standard ISO/DIS 4223-1:2025(en)

Tyre industry — Vocabulary —
Part 1:
Pneumatic tyres
1 Scope
This document defines a number of significant terms related to pneumatic tyres, i. e. tyres suitable for
containing a gas at a pressure which can be adjusted. This document specifies the corresponding codes,
symbols and values for these tyres.
This document specifies the corresponding codes, symbols and values for these tyres.
NOTE 1 For other terms used in this field and their equivalents in other languages, see ISO 3877 (all parts). For terms
and definitions relating to wheels and rims, see ISO 3911.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 3911, Wheels and rims for pneumatic tyres — Vocabulary, designation and marking
ISO 16992, Passenger car tyres — Spare unit substitutive equipment (SUSE)
ISO 18106, Passenger car, commercial vehicle, truck and bus tyres — Methods for measuring snow grip
performance — Loaded new tyres
ISO 18805, Tyre classification — Agricultural, forestry and construction machines
ISO 19447, Passenger car tyres — Method for measuring ice grip performance — Loaded new tyres
3 Terms, definitions and symbols
For the purposes of this document, the terms, definitions and symbols given in ISO 3911 and ISO 18805 and
the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— — IEC Electropedia: available at https://www.electropedia.org/
— — ISO Online browsing platform: available at https://www.iso.org/obp
ISO /FDIS 4223-1:2026(en)
3.1 Terms relating to category of use
3.1.1 3.1.1
normal tyre
tyre intended for use on public streets, roads and highways and that are not marked with “M+S” (or other
variations) or severe snow or special usetyre (3.1.2use tyre (3.1.2)) designations
3.1.2 3.1.2
special use tyre
tyre intended for mixed use both on- and off-road or for other special duty and primarily designed to initiate
and control vehicle motion in off-road conditions
Note 1 to entry: Examples of special use tyre designations are ET (3.6.1.1.29(3.6.1.1.29),), MPT (3.6.1.1.30(3.6.1.1.30),),
ML (3.6.1.1.16(3.6.1.1.16),), and POR (3.6.1.1.31(3.6.1.1.31).).
3.1.2.1 3.1.2.1
professional off-road tyre
POR tyre
special usetyre (3.1.2use tyre (3.1.2)) primarily used for service in severe off-road conditions
3.1.3 3.1.3
snow tyre
mud and snow tyre
tyre whose tread (3.4.4(3.4.4)) pattern, tread compound or structure (3.3.1(3.3.1)) is primarily designed to
achieve in winter conditions (e.g. either on snow or on mud and sand, or both) a performance better than that
of a normal tyre (3.1.1(3.1.1)) with regard to its ability to initiate or control vehicle motion
Note 1 to entry: It is identified by a combination of the letters “M” and “S”, e. g. M+S, M&S, M.S.
3.1.3.1 3.1.3.1
ice grip tyre
passenger car snow tyre (3.1.3(3.1.3)) that is classified as a severe snow use tyre (3.1.4(3.1.4)) and additionally
designed to be used on road surfaces covered with ice
Note 1 to entry: An ice grip tyre shall conform to ISO 19447.
[3]
Note 2 to entry: An ice grip tyre that conforms to UN Regulation No. 117 [2] shall be marked with the ice grip symbol
(see Figure 1Figure 1):):
Figure 1 — Ice grip symbol (ISO 7000-3964)
2 © ISO 2017 – All rights reserved

ISO/DISFDIS 4223-1:20252026(en)
3.1.4 3.1.4
severe snow use tyre
tyre for use in severe snow conditions
tyre whose tread (3.4.4(3.4.4)) pattern, tread compound or structure (3.3.1(3.3.1)) is specifically designed
based on performance testing using ISO 18106 and which is identified by an “Alpine” or “3 Peak Mountain
Snow Flake (3PMSF)” symbol
Note 1 to entry: Regional standards and regulatory requirements can apply for dimensions and performance criteria
for severe snow use tyres as well as for the placement of the 3 Peak Mountain Snow Flakepeak mountain snow flake
(3PMSF) symbol (see Figure 2Figure 2).).

Figure 2 — 3 Peak Mountain Snow Flakepeak mountain snow flake (3PMSF) symbol
3.1.5 3.1.5
temporary-use spare tyre
tyre different from a tyre intended to be fitted to any vehicle for normal driving conditions but intended only
for temporary use under restricted driving conditions
3.1.5.1 3.1.5.1
T-type temporary-use spare tyre
temporary-use spare tyre (3.1.5(3.1.5)) designed for use at an inflation pressure higher than those established
for standard and reinforced tyres (3.8.11(3.8.11))
Note 1 to entry: It is designated with the “T” prefix.
3.1.6 3.1.6
not for highway service tyre
NHS tyre
tyre primarily designed for use outside of public roads, but suitable for temporary or incidental use on public
roads and identified with the letters “NHS” (3.6.1.1.8(3.6.1.1.8))
EXAMPLESEXAMPLE Earth-mover, industrial, agricultural equipment and motorcycles tyres can be not for
highway service tyres.
Note 1 to entry: Motorcycle tyres that are marked with “NHS” shall not be used on public roads.
ISO /FDIS 4223-1:2026(en)
3.1.7 3.1.7
traction tyre
tyre intended to be fitted primarily to the drive axle(s) of a vehicle to maximize force
transmission in various circumstances
Note 1 to entry: Traction tyres can be marked with “TRACTION”.
3.2 Terms relating to service description
3.2.1 3.2.1
service description
tyre identification, in addition to the tyre size designation (3.6.1(3.6.1),), which consists of one or two load
indices (LI) (3.2.1.1(3.2.1.1)) and a speed symbol (SS) (3.2.1.2(3.2.1.2))
Note 1 to entry: When two load indices are used, these indicate the load carrying capacity in single and dual fitment.
EXAMPLE 91H or 121/119S.
3.2.1.1 3.2.1.1
load index
LI
numerical code which indicates a reference load used to define the load carrying capacity of the tyre, which
can depend on operating conditions and tyre type
Note 1 to entry: The standardized load indices and the assigned reference loads are specified in Table A.1Table A.1.
3.2.1.2 3.2.1.2
speed symbol
SS
alpha or alpha-numeric code which indicates the speed category (3.2.1.3(3.2.1.3)) of the tyre, which can
depend on operating conditions and tyre type
Note 1 to entry: The standardized speed symbols are specified in Table A.2Table A.2.
3.2.1.3 3.2.1.3
speed category
maximum speed which the tyre can sustain, expressed by the speed symbol, and which is part of the service
description (3.2.1(3.2.1))
Note 1 to entry: The speed categories assigned to the standardized speed symbols are specified in Table A.2Table A.2.
3.2.1.4 3.2.1.4
additional service description
secondary service description identifying a special type of service at which the tyre is allowed to operate in
addition to the main service description
Note 1 to entry: The additional service description shall be marked within a circle and shall be located close to the main
service description.
Note 2 to entry: The additional service description shall consist of either one or two load indices that are greater than,
and a speed symbol that indicates a speed category that is less than, that of the main service description or one or two
load indices that are lower than or equal to and a speed symbol that indicates a speed category that is greater than that
of the main service description.
4 © ISO 2017 – All rights reserved

ISO/DISFDIS 4223-1:20252026(en)
3.3 Terms relating to structure
3.3.1 3.3.1
structure
technical characteristics of the tyre’s structure
3.3.1.1 3.3.1.1
diagonal structure
bias-ply structure
cross-ply structure
structure (3.3.1(3.3.1)) in which the ply cords (3.4.5(3.4.5)) that extend to the beads (3.4.1(3.4.1)) are laid at
alternate angles of substantially less than 90° to the centreline of the tread (3.4.4(3.4.4))
3.3.1.1.1 3.3.1.1.1
diagonal tyre
tyre having a diagonal structure (3.3.1.1(3.3.1.1))
3.3.1.2 3.3.1.2
bias-belted structure
structure (3.3.1(3.3.1)) in which the ply cords (3.4.5(3.4.5)) that extend to the beads (3.4.1(3.4.1)) are laid at
alternate angles of substantially less than 90° to the centreline of the tread (3.4.4(3.4.4)) and are restricted by
a belt (3.4.10(3.4.10)) comprising one or more layers of substantially inextensible cord (3.4.5(3.4.5)) material
3.3.1.2.1 3.3.1.2.1
bias-belted tyre
tyre having a bias-belted structure (3.3.1.2(3.3.1.2))
3.3.1.3 3.3.1.3
radial structure
structure (3.3.1(3.3.1)) in which the ply cords (3.4.5(3.4.5)) that extend to the beads (3.4.1(3.4.1)) are laid at
substantially 90° to the centreline of the tread (3.4.4(3.4.4)) in a zone including most of the sidewall
(3.4.2(3.4.2)) and located outside the bead (3.4.1(3.4.1)) and the essentially inextensible circumferential belt
(3.4.10(3.4.10)) that stabilizes the carcass (3.4.8(3.4.8))
3.3.1.3.1 3.3.1.3.1
radial tyre
tyre having a radial structure (3.3.1.3(3.3.1.3))
3.3.1.3.2 3.3.1.3.2
extended radial structure
radial structure (3.3.1.3(3.3.1.3)) in which the ply cords (3.4.5(3.4.5)) that extend to the beads (3.4.1(3.4.1))
are not laid substantially at 90° to the centre line of the tread (3.4.4(3.4.4)) across the complete cross section
of the tyre
3.4 Terms relating to main components
3.4.1 3.4.1
bead
part of the tyre shaped to fit the rim (3.7.12(3.7.12)) and having a core made of one or several essentially
inextensible strands with the plies (3.4.6(3.4.6)) wrapped around the core
ISO /FDIS 4223-1:2026(en)
3.4.2 3.4.2
sidewall
portion of the tyre between the tread (3.4.4(3.4.4)) and the bead (3.4.1(3.4.1))
3.4.3 3.4.3
sidewall rubber
rubber layer on the sidewall (3.4.2(3.4.2)) of the tyre and over the carcass (3.4.8(3.4.8),), which can include
ornamental or protective ribs, tyre labelling and markings, and moulded fitting lines
3.4.3.1 3.4.3.1
rim protector
feature incorporated into the lowersidewall (3.4.11lower sidewall (3.4.11)) area of the tyre which is intended
to protect the rim (3.7.12(3.7.12)) flange from damage
3.4.4 3.4.4
tread
part of a tyre which comes into contact with the ground
3.4.5 3.4.5
cord
textile or non-textile strands (threads) used in various components of the tyre carcass (3.4.8(3.4.8))
EXAMPLESEXAMPLE Plies (3.4.6(3.4.6),), belts (3.4.10(3.4.10),), breakers (3.4.9(3.4.9).).
3.4.6 3.4.6
ply
layer of rubber-coated parallel cords (3.4.5(3.4.5))
3.4.7 3.4.7
inner liner
layer of rubber on the inside of the carcass (3.4.8(3.4.8)) used especially in tubeless tyres to minimize air loss
3.4.8 3.4.8
carcass
part of a tyre other than the tread (3.4.4(3.4.4)) and the sidewall rubber (3.4.3(3.4.3)) which, when inflated,
bears the load
3.4.9 3.4.9
breaker
intermediate ply (3.4.6(3.4.6)) not extending to the bead (3.4.1(3.4.1))
3.4.10 3.4.10
belt
bracing ply
layer of material underneath the tread (3.4.4(3.4.4),), laid substantially in the direction of the tread centreline,
that restricts the carcass (3.4.8(3.4.8)) circumferentially
3.4.11 3.4.11
lower sidewall
area below the line of maximum section width (3.5.1(3.5.1)) of the tyre, visible when the tyre, fitted to a rim
(3.7.12(3.7.12),), is viewed from the side
3.4.12 3.4.12
tread groove
space between the adjacent ribs or blocks in the tread (3.4.4(3.4.4)) pattern
6 © ISO 2017 – All rights reserved

ISO/DISFDIS 4223-1:20252026(en)
3.4.13 3.4.13
tread wear indicator
projection within the tread grooves (3.4.12(3.4.12)) designed to give a visual indication of the degree of wear
of the tread (3.4.4(3.4.4))
3.4.14 3.4.14
chafer
material in the bead (3.4.1(3.4.1)) area to protect the carcass (3.4.8(3.4.8)) against rim (3.7.12(3.7.12)) chafing
3.5 Terms relating to dimensions (see Figure 3Figure 3))

a
Specified rim width.
Figure 3 — Dimensions
ISO /FDIS 4223-1:2026(en)
3.5.1 3.5.1
section width
S
linear distance between the outside of the sidewalls (3.4.2(3.4.2)) of an inflated pneumatic tyre, when fitted
on a measuring rim (3.7.10(3.7.10),), excluding elevations due to labelling (markings), decorations, protective
bands or ribs, or rim protector (3.4.3.1(3.4.3.1))
3.5.2 3.5.2
overall width
W
linear distance between the outsides of the sidewalls (3.4.2(3.4.2)) of an inflated pneumatic tyre, when fitted
on a measuring rim (3.7.10(3.7.10),), including labelling (marking), decoration, protective bands or ribs, and
rim protector (3.4.3.1(3.4.3.1),), and in the case of tyres where the tread (3.4.4(3.4.4)) is wider than the section
width (3.5.1(3.5.1),), the overall width corresponds to the tread width
3.5.3 3.5.3
maximum overall tyre width in service
overall width (3.5.2(3.5.2)) plus
a) a) manufacturing tolerances,; and
b) b) tolerance for service growth
3.5.4 3.5.4
section height
H
half the difference between the overall diameter (3.5.5(3.5.5)) and the nominal rim diameter (3.5.9(3.5.9))
3.5.5 3.5.5
overall diameter
D
o
diameter of an inflated pneumatic tyre, when fitted on a measuring rim (3.7.10(3.7.10),), at the outermost
surface of the tread (3.4.4(3.4.4),), applying to new tyres (3.8.3(3.8.3)) or newly retreaded tyres (3.8.9(3.8.9))
3.5.6 3.5.6
static maximum overall tyre diameter in service
D
os
overall diameter (3.5.5(3.5.5)) plus
a) a) manufacturing tolerances,; and
b) b) tolerance for service growth
3.5.7 3.5.7
dynamic maximum overall tyre diameter in service
D
od
overall diameter (3.5.5(3.5.5)) plus
a) a) manufacturing tolerances,;
b) b) tolerance for service growth,; and
c) c) allowance for dimensional changes due to centrifugal force
8 © ISO 2017 – All rights reserved

ISO/DISFDIS 4223-1:20252026(en)
Note 1 to entry: This definition applies only to motorcycle tyres; the allowance in 3.5.73.5.7 c) shall be taken into
account when designing for tyre clearances.
3.5.8 3.5.8
nominal aspect ratio
H/S
ratio of the tyre [on its theoretical rim (3.7.12(3.7.12)])] nominal section height (3.5.4(3.5.4)) to the nominal
sectionnominalsection width (3.5.10(3.5.10)) multiplied by 100
3.5.9 3.5.9
nominal rim diameter
D
r
conventional number corresponding to the diameter of the rim (3.7.12(3.7.12)) expressed either as a size code
(number less than 100) or in millimetres (number greater than 100), but not as both
Note 1 to entry: See Table A.3Table A.3 for the nominal rim diameters, expressed in millimetres, that shall apply to
nominal rim diameters expressed by codes.
3.5.10 3.5.10
nominal section width
S
N
section width (3.5.1(3.5.1)) indicated in the tyre size designation (3.6.1(3.6.1),), and used for calculation of tyre
dimensions
Note 1 to entry: Regional tyre standards have used “SN”.
3.5.11 3.5.11
specified rim diameter
diameter of the intersection of the axial projections of the bead seat and the flange of a rim (3.7.12(3.7.12))
Note 1 to entry: The specified rim diameters recommended to be used for nominal rim diameters (3.5.9(3.5.9))
expressed by codes are specified in Table A.4Table A.4.
Note 2 to entry: Bead seat and flange are defined in ISO 3911.
3.6 Terms, definitions and symbols of designation
3.6.1 3.6.1
tyre size designation
designation showing:
— — the nominal sectionnominalsection width (3.5.10(3.5.10););
— — the nominal aspect ratio (3.5.8(3.5.8););
— — indication of the structure (3.3.1(3.3.1)) placed in front of the nominal rim diameter (3.5.9(3.5.9))
marking, as follows:
— — for diagonal tyres (3.3.1.1.1(3.3.1.1.1):): the symbol “-” or the letter “D”;
— — for bias-belted tyres (3.3.1.2.1(3.3.1.2.1):): the letter “B”;
— — for radial tyres (3.3.1.3.1(3.3.1.3.1):): the letter “R”;
ISO /FDIS 4223-1:2026(en)
— — for run flat tyres (3.8.12(3.8.12):): the letters “RF”;
— — a conventional number denoting the nominal rim diameter (3.5.9(3.5.9)) and corresponding to its
diameter expressed either by codes (numbers below 100) or in millimetres (numbers above 100)
Note 1 to entry: Additional indications, letters, groups of letters and numbers can be part of the tyre size designation
depending on the intended use of the tyre.
EXAMPLE 165/80R15, 24.00-25 NHS.
3.6.1.1 3.6.1.1
additional tyre designation
additional letter or symbol that may also be part of the tyre size designation (3.6.1(3.6.1),), to differentiate
between tyres designed for different service conditions
3.6.1.1.1 3.6.1.1.1
T
letter placed immediately in front of the nominal sectionnominalsection width (3.5.10(3.5.10)) to identif
...