TABLE A-1 Items Common to J1269 and J2452

Item

Specification

Test wheel diameter

1.7 m (67 in.)

Measurement methodsa

Force

 

Torque

Surface

80-grit paperb

Allowed ambient temperature

20°C (68°F) ≤ T ≤ 28°C (82°F)

Reference temperature

24°C (75°F)

a J1269 also allows rolling resistance determination by measurement of electrical power consumption, but this method is no longer in common use.

b This is actually an emery cloth. J2452 contains a surface conditioning procedure for the material.

Table A-1. The practices use the same test rims. The normally used test rims are the measuring rims,4 but other rims approved in a tire and rim standards organization yearbook such as that of the Tire and Rim Association may be used. The rim used is always noted in the test report because rim width affects test results.

DIFFERENCES BETWEEN THE TWO PRACTICES

There are a number of differences between the two practices, which are detailed below.

Inflation Pressure and Load

Tire rolling resistance is dependent on inflation pressure and load. In both test practices inflation pressure is defined in terms of a base pressure. Base pressure is not defined in precisely the same manner in the two practices. In J1269 it is the inflation pressure molded on the tire sidewall together with the maximum load. This is straightforward for P-tires, but it only applies to single-tire loading in the case of LT-tires.5 In J2452, P-tire base pressures are defined in the first table in the recommended practice.

4

The design/measuring rim is the specific rim assigned to each specific tire designation to determine basic tire dimensions. This rim is specified for each tire designation in the yearbooks of tire and rim standards organizations such as the Tire and Rim Association, Inc.

5

P-tires are passenger tires. LT-tires are light truck tires.



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