SAE J2452 is a standard defined by the
Society of Automotive Engineers
SAE International is a global professional association and standards organization based in Warrendale, Pennsylvania, United States. Formerly the Society of Automotive Engineers, the organization adopted its current name in 2006 to reflect bot ...
to measure the
rolling resistance
Rolling resistance, sometimes called rolling friction or rolling drag, is the force resisting the Motion (physics), motion when a body (such as a ball, tire, or wheel) Rolling, rolls on a surface. It is mainly caused by Plasticity (physics), non- ...
of
tire
A tire (North American English) or tyre (Commonwealth English) is a ring-shaped component that surrounds a Rim (wheel), wheel's rim to transfer a vehicle's load from the axle through the wheel to the ground and to provide Traction (engineeri ...
s. Where the older standard,
SAE J1269, produces measurements of rolling resistance under steady-state (i.e. thermally equilibrated) operating conditions, SAE J2452 produces measurements during a transient history of speed that is intended to mimic a vehicle
coastdown event. During the SAE J2452 test, the tire is not in thermal equilibrium, but the coastdown event is rapid enough that the tire operates at a roughly iso-thermal condition.
Either procedure may be used to investigate the effects of different vehicle loads (weight), tire pressures and vehicle speeds.
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 Z
β (a + bV + cV
2)''
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).
References
Tires
Automotive standards
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