Following is a cut and paste from an earlier post I made about the benefits of saving rotational weight vs. non-rotational -
"I played around once trying to figure out how much benefit could be realized from saving a pound of rotating weight compared to saving a pound of non-rotating weight. The answer is - it depends. The calculation is complicated by the fact that weight is not evenly distributed over the radius of the wheel/tire combination. And each combination has a different distribution.
However if 100% of the weight of the wheel/tire is carried on the tread surface (a theoretical worst case), each pound of rotating weight would be worth two pounds of fixed weight. This for both acceleration and deceleration, but not cornering or unsprung weight.
But since the real world distribution of weight is not on 100% on the tread, the real benefit is less than 2:1. So eyeballing it for a typical combination 25 lbs tire (carrying most of its weight on the tread and all of it close to the tread) and 16 lbs wheel (carrying about half its weight on the rim close to the tread), I would approximate the benefit at around 1.7:1"
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Chuck - '86 Cab, '77 Targa, '85 toyota 4wd rain mobile
http://www.cheaterswayside.com/911/