Editorial Type:
Article Category: Research Article
 | 
Online Publication Date: 01 Jun 2007

Fidelity of J1269 and J24523

and
Page Range: 94 – 117
DOI: 10.2346/1.2737559
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Abstract

This study compares data from the two Society of Automotive Engineers test methods for rolling resistance: J-2452 (Stepwise Coast-Down) and J-1269 (Equilibrium) steady state. The ability of the two methods to evaluate tires was examined by collecting data for 12 tires. The data were analyzed and the data showed that the two methods ranked the tires the same after the data were regressed and the rolling resistance magnitude was calculated at the Standard Reference Condition. In addition, analysis of the two methods using this matched set of testing provided an opportunity to evaluate each of these test standards against the other. It was observed that each test has merits absent from the other.

Keywords: rolling resistance; fuel economy; coast-down; standard reference condition; SAE J-1269; SAE J-2452
Copyright: The Tire Society
FIG. 1.
FIG. 1.

This figure presents SAE J-1269 experimental rolling resistance data at each test point and each of the 12 tire specifications.

FIG. 2.
FIG. 2.

This figure presents SAE J-1269 experimental rolling resistance data averaged for each of the tire constructions and at each test.

FIG. 3.
FIG. 3.

This figure presents SAE J-2452 experimental rolling resistance for each of the tire constructions and at each test.

FIG. 4.
FIG. 4.

This figure presents SAE J-2452 experimental rolling resistance data averaged for each of the tire constructions at each test point and at the 115 km/hr speed point.

FIG. 5.
FIG. 5.

This figure presents SAE J-2452 experimental rolling resistance data averaged for each of the tire constructions at each test point and at the 84 km/hr speed point.

FIG. 6.
FIG. 6.

This figure presents SAE J-2452 experimental rolling resistance data averaged for each of the tire constructions at each test point and at the 59 km/hr speed point.

FIG. 7.
FIG. 7.

This figure presents SAE J-2452 experimental rolling resistance data averaged for each of the tire constructions at each test point and at the 38 km/hr speed point.

FIG. 8.
FIG. 8.

This figure presents SAE J-2452 experimental rolling resistance data averaged for each of the tire constructions at each test point and at the 24 km/hr speed point.

FIG. 9.
FIG. 9.

This figure presents SAE J-2452 experimental rolling resistance data averaged for each of the tire constructions at each test point at the 15 km/hr speed point.

FIG. 10.
FIG. 10.

Shows the standard deviation versus load step for different tire groups and speeds. The reason for the variations is unclear.

FIG. 11.
FIG. 11.

The image to the left is a plot of the regressed SRC values for all 12 tires, with SAE J-1269 compared to SAE J-2452. The dashed line indicates perfect fidelity. The image on the right is the same plot showing the pooled variations of each method.

FIG. 12.
FIG. 12.

Shows the SAE Recommended Practice Load and Inflation Pressure points, in N and kPa; demonstrates that the actual test data do not overlap the Standard Reference Condition point (SRC).

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