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Old 02-08-2011, 04:30 PM   #89 (permalink)
abell75
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Join Date: Nov 2010
Location: St. Louis
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Grand Prix - '02 Pontiac Grand Prix GP
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The reason we see several rules of thumb for the translation from wheel&tire weight to 'normal' weight is that for a given wheel/tire combo, there can be various moments of inertia.

Rotational dynamics and linear dynamics don't translate so easily.

To figure out the difference that new wheels/tires would make to acceleration, you need to apply rotational dynamics to the before and after situations. The trouble is that while finding weights is easy enough, moments of inertia are not so readily available Others have already said it - for a given wheel/tire weight, you want the mass as close to the axis as you can get.

Hoop and Cylinder Motion
Rotational Work and Kinetic Energy

density of rubber is about 1500 kg/cubic meter (internet stats vary a lot here)
density of iron (steel) is about 7850 kg/cm
aluminum: 2600 kg/cm
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