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      09-24-2008, 04:42 AM   #30
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Drives: E60&E92
Join Date: Jul 2008
Location: west

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Originally Posted by swamp2 View Post
Large I values in your wheels not only affect acceleration but also braking and turning, all negatively.
But of course this doesn't apply to the 20's on the GT-R. Because it is big, special, and was designed for 20's. The magic electronics and suspension on the car just eliminate inertia from the equation. I am surprised Nissan hasn't figured out how to eliminate the force a gravity while they are at it. Fact is Nissan picked 20's for the GT-R.

Originally Posted by swamp2 View Post
There is a similar reason to be greatly concerned with unsprung mass - that of the suspension and everything that moves along with the suspension. High unsprung mass is even worse than high sprung mass (say like the car body or a passenger).
Glad to see you agree. 20's that weigh 3-4 lbs lighter per/wheel than the stock 19's, will have less unsprung weight/mass.

Originally Posted by swamp2 View Post
Lastly (and again, and again...) these effects are NOT huge. We are probably talking tenths of seconds in most acceleration metrics and maybe a couple feet in braking metrics will separate 18s, 19s and 20s. Very rough educated guesses here. However, do recall that saving X lb in a rotating component is MUCH more significant than saving the same X lb from a non-rotating component.
Again you agree, these effects are not huge.

I will say it again. 20's for the street and a seperate 18 inch track setup. It isn't that difficult.