ASTM F1016-07(2013)e1

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Designation: F1016 − 07 F1016 − 07 (Reapproved 2013)
Standard Practice for
Linear Tire Treadwear Data Analysis
This standard is issued under the fixed designation F1016; 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 (´) indicates an editorial change since the last revision or reapproval.
ε NOTE—Editorial corrections made throughout in June 2013.
1. Scope
1.1 This practice describes the elementary linear regression analysis of basic treadwear data as obtained according to Test
Method F421 and Test Method 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 Test Method 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, R , 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.
2. Referenced Documents
2.1 ASTM Standards:
F421 Test Method for Measuring Groove and Void Depth in Passenger Car Tires
F538 Terminology Relating to the Characteristics and Performance of Tires
F762 Test Method for Determining Change in Groove (or Void) Depth With Distance Traveled for Passenger Car Tires
3. Terminology
3.1 Definitions:
3.1.1 average tire tread depth, [L],n—the average of all tire groove (void) depth measurements. F538
3.1.2 break-in, [L],n—one or more periods of initial standardized tire operation during which tire is brought to the state which
will lead to more consistent test results. F538
3.1.3 fastest wearing groove, [L],n—the circumferential groove with the minimum life expectancy. F538
3.1.4 fastest wearing location, [L],n—that location which exhibits the highest percent tread (depth) loss as calculated in 6.1.1.
F538
3.1.5 groove, average depth, [L],n—the average of all tire groove depth measurements in a single groove. F538
3.1.6 projected treadlife, [L],n—the test distance that gives h as the average tread depth; where h is the height of treadwear
indicator above groove (or void) base. F538
3.1.7 test distance, [L],n—distance traveled by a vehicle after tire break-in. F538
This practice is under the jurisdiction of ASTM Committee F09 on Tires and is the direct responsibility of Subcommittee F09.30 on Laboratory (Non-Vehicular) Testing.
Current edition approved July 1, 2007June 1, 2013. Published July 2007September 2013. Originally approved in 1986. Last previous edition approved in 20012007 as
F1016 – 93 (2001).F1016 – 07. DOI: 10.1520/F1016-07.10.1520/F1016-07R13E01.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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F1016 − 07 (2013)
4. Summary of Practice
4.1 This practice provides a calculation procedure for linear regression analysis of treadwear data to be used in the tire industry
for assessing tire treadwear performance.
4.2 No specific mathematical formulas are given for the customary least-squares calculations used for linear regression
parameter evaluation since these calculation algorithms are readily available with electronic hand calculators or statistical software
for personal computers, or both. Terms are defined for slope, intercept, and coefficient of determination.
5. Significance and Use
5.1 The purpose of this practice is to standardize the meaning and derivation of some terms and indexes that are commonly used
to characterize treadwear.
5.1.1 There is no intent to recommend either of the two treadwear performance indexes: distance per unit loss of tread depth
or loss of tread depth per distance unit.
6. Calculation
6.1 Use the following calculations and terms to report treadwear:
6.1.1 The percentage tread (depth) loss (PTL) expresses the loss of tread depth as a percent of the initial tread depth (to the
tread-depth indicators), as follows:
¯ ¯
X 2 X
i k
PTL 5 100 (1)
F G
¯
X 2 h
i
¯ ¯
X 2 X
i k
PTL 5 3100 (1)
F G
¯
X 2 h
i
where:
X¯ = average tread depth after a break-in (see 3.1.1 or 3.1.2),
i
X¯ = average tread depth at a given observation or test distance (see 3.1.1 or 3.1.7), and
k
h = height of treadwear indicator above groove (or void) base.
6.1.2 The percentage tread (depth) remaining (PTR) expresses the remaining tread depth as a percent of the initial tread depth
(to the tread-depth indicators), as follows:
PTR 5 100 2 PTL (2)
6.1.3 The rate of wear, RW, is obtained as the slope, b (either for SI or inch-pound units), of the regression line of average tire
tread depth (y-variable) versus the test distance (x-variable). See 3.1.1 an
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