ASTM F1016-93(2001)
(Practice)Standard Practice for Linear Tire Treadwear Data Analysis
Standard Practice for Linear Tire Treadwear Data Analysis
SCOPE
1.1 This practice describes the elementary linear regression analysis of basic treadwear data as obtained according to Test Method F421 and Practice F762.
1.2 The basic treadwear data are obtained as groove depth loss measurements by procedures described in Test Method F421 after a series of test cycles (test distances under specified conditions) according to Practice F762.
1.3 A linear regression analysis is performed for the relationship between average tire tread depth and the test distance traveled by the test vehicle, on which the test tires are mounted. From this analysis a rate of wear is determined: groove depth loss per unit distance.
1.4 Linear treadwear is defined as an essentially constant rate of wear, after break-in, which results in a linear regression coefficient of determination, R2, equal to or greater than 0.95 when obtained for a data set where the number of measurement intervals, n, is at least 3. Each measurement interval represents a specific test distance.
1.5 This practice is not applicable to the prediction of treadlife for tires that exhibit non-linear or irregular treadwear.
1.6 Evaluation parameters are given for both SI and inch-pound units; either may be used. The evaluation parameters as defined are ones typically used in the tire testing industry and no special claim is made for superiority of these parameters and terms over other terms and parameters that may be developed.
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Designation:F1016–93 (Reapproved 2001)
Standard Practice for
Linear Tire Treadwear Data Analysis
This standard is issued under the fixed designation F 1016; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope F 762 Test Method for Determining Change in Groove (or
Void) Depth With Distance Traveled for Passenger Car
1.1 This practice describes the elementary linear regression
Tires
analysis of basic treadwear data as obtained according to Test
Method F 421 and Test Method F 762.
3. Terminology
1.2 The basic treadwear data are obtained as groove depth
3.1 Definitions:
loss measurements by procedures described in Test Method
3.1.1 average tire tread depth, [L], n—the average of all tire
F 421 after a series of test cycles (test distances under specified
groove (void) depth measurements.
conditions) according to Test Method F 762.
3.1.2 break-in, [L], n—one or more periods of initial stan-
1.3 A linear regression analysis is performed for the rela-
dardized tire operation during which tire is brought to the state
tionship between average tire tread depth and the test distance
which will lead to more consistent test results.
traveledbythetestvehicle,onwhichthetesttiresaremounted.
3.1.3 groove, average depth, [L], n—the average of all tire
From this analysis a rate of wear is determined: groove depth
groove depth measurements in a single groove.
loss per unit distance.
3.1.4 projected treadlife, [L], n—the test distance that gives
1.4 Linear treadwear is defined as an essentially constant
h as the average tread depth; where h is the height of treadwear
rate of wear, after break-in, which results in a linear regression
indicator above groove (or void) base.
coefficient of determination, R , equal to or greater than 0.95
3.1.5 test distance, [L], n—distance traveled by a vehicle
whenobtainedforadatasetwherethenumberofmeasurement
after tire break-in.
intervals, n, is at least 3. Each measurement interval represents
a specific test distance.
4. Summary of Practice
1.5 This practice is not applicable to the prediction of
4.1 This practice provides a calculation procedure for linear
treadlife for tires that exhibit non-linear or irregular treadwear.
regression analysis of treadwear data to be used in the tire
1.6 Evaluation parameters are given for both SI and inch-
industry for assessing tire treadwear performance.
pound units; either may be used. The evaluation parameters as
4.2 No specific mathematical formulas are given for the
defined are ones typically used in the tire testing industry and
customary least-squares calculations used for linear regression
no special claim is made for superiority of these parameters
parameter evaluation since these calculation algorithms are
and terms over other terms and parameters that may be
readily available with electronic hand calculators or statistical
developed.
software for personal computers, or both.Terms are defined for
slope, intercept, and coefficient of determination.
2. Referenced Documents
2.1 ASTM Standards:
5. Significance and Use
F 421 Test Method for Measuring Groove and Void Depth
5.1 The purpose of this practice is to standardize the
in Passenger Car Tires
meaning and derivation of some terms and indexes that are
F 538 Terminology Relating to the Characteristics and Per-
2 commonly used to characterize treadwear.
formance of Tires
5.1.1 There is no intent to recommend either of the two
treadwear performance indexes: distance per unit loss of tread
This practice is under the jurisdiction ofASTM Committee F09 on Tires and is depth or loss of tread depth per distance unit.
the direct responsibility of Subcommittee F09.30 on Laboratory (Non-Vehicular)
Testing.
6. Calculation
Current edition approved Feb 15, 1993. Published May 1993. Originally
6.1 Use the following calculations and terms to report
published as F 1016 – 86. Last previous edition F 1016 – 86.
Annual Book of ASTM Standards, Vol 09.02. treadwear:
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F1016
6.1.1 The percentage tread (depth) loss (PTL) expresses the 7)) to giveTLI, a treadlife index, or on the basis of rate of wear
loss of tread depth as a percent of the initial tread depth (to the ((Eq 8)) to give TWI, a treadwear index. The two are
tread-depth indicators), as follows: equivalent if the initial tread depth of the candidate tire is equal
to that of the control tire.
¯ ¯
X 2 X
i k
PTL 5 100 (1)
F G
% loss in control tire
¯
X 2 h
i
TLI 5 3 100 (7)
% loss in candidate tire
where:
RW of control tire
¯ TWI 5 3 100 (8)
X = average tread depth after a break-in (see 3.1.1 or
i RW of candidate tire
3.1.2),
6.1.5.1 Theinverseofeachoftheseexpressionsmayalsobe
¯
X = average tread depth at a given observation or test
k
used.
distance (see 3.1.1 or 3.1.5), and
h = height of treadwear indicator above groove (or void)
7. Projected Treadlife Considerations
base.
6.1.2 The percentage tread (depth) remaining (PTR) ex-
7.1 Projected treadlife is usually calculated for each tire in a
presses the remaining tread depth as a percent of the initial
set so that tire-to-tire variances, as well as overall means, may
tread depth (to the tread-depth indicators), as follows:
be considered.
PTR 5 100 2 PTL (2)
...
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