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Old 01-24-2013, 08:02 AM   #87 (permalink)
aardvarcus
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Broad generalizations may get you close, but there can't be a one size fits all equation. Wheels and tires of different masses cause you to build different amounts of angular momentum in the sets. (In addition to the additional RR, gearing, and Aero differences.) Angular momentum equations are all based off the lever arm (distance from the center) to where the mass lies. Two tires of equal diameter and equal weights could have significantly different amounts of angular momentum required to be built to get to the same speed. For example, a heavy tire on a lightweight alloy rim will have its mass on average further from the center, while a lightweight tire on a heavy steel rim will have it’s mass closer to the center. They may weigh the same, but the heavy tire light rim combo will take more force to get rotating.

The real “answer” is that you will have to evaluate your wheel and tire situation on a case by case basis. Light wheel and tire combinations will have a far greater effect in city stop and go driving as compared to highway driving.
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