Quote:
Originally Posted by abshnasko
so in conclusion (correct me if im wrong):
1. a larger rim + tire combo CAN be lighter if attention is paid, helping FE
2. larger rim is generally less aerodynamic and takes a wider tire, hurting FE
3. larger rim size means that more of the LRR tires will fit (possible negating the effect of #2?), helping FE
4. larger rim and OD reduces rpm's, helping FE
about a larger rim being less aerodynamic... would some of this be countered some if I installed dams in front of the wheels? Or would it have to be skirts...
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(1) Right! If the overall mass is less,and the mass is not concentrated out near the tread,the wheel/tire will be lighter "flywheel". (2) the larger rim need not be less aero if it is more like an optimized disc ( pie-pan ).If the wheel is WIDER,then it will a larger frontal area,crashing into more air as it goes. (3) yes,although it didn't work for me in the case of the Michelin MXV Green-X radials. (4) Only a larger overall circumference of the tire will effect revolutions per mile,and typically,in a clean-sheet design for a high-mpg car,engineers would spec out a slow-turning tire for the LLR.