SAE J2452 is a standard defined by the Society of Automotive Engineers to define the rolling resistance

Rolling resistance

Rolling resistance, sometimes called rolling friction or rolling drag, is the resistance that occurs when a round object such as a ball or tire rolls on a flat surface, in steady velocity straight line motion. It is caused mainly by the deformation of the object, the deformation of the surface, or...

 of tire

Tire

A tire or tyre is a ring-shaped covering that fits around a wheel rim to protect it and enable better vehicle performance by providing a flexible cushion that absorbs shock while keeping the wheel in close contact with the ground...

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The rolling resistance coefficient (RRC) indicates the amount of force required to overcome the hysteresis of the material as the tire rolls. Tire pressure, vehicle weight and velocity all play a role in how much force is lost to rolling resistance.

The basic model equation for SAE J2452 is:

Rolling Resistance ( N / Lbs) = P^α x Z^β x (a + bxV + cxVxV)

where:

P is the tire inflation pressure ( kPa / psi)

Z is the applied load for vehicle weight ( N /Lbs)

V is the vehicle speed ( km/h / mph)

alpha, beta, a, b, c are the coefficients for the model.

The units of the coefficients are matched to the units used in the model, i.e. ( metric / Imperial)

This model is newer than SAE J1269

SAE J1269

SAE J1269 is a standard test defined by the Society of Automotive Engineers to measure the rolling resistance of tires.The rolling resistance coefficient thus measured indicates the proportion of energy that is lost to the hysteresis of the material as the tire rolls....

and provides more accuracy over a range of different vehicle loads (weight), tire pressures and vehicle speeds.