hehe ya we will.

just another comparison if ti were me, I am not sure what your goal is as far as traction,

but a exmaple:

for drag racing: I am going to run a 15" wheel over a 18" wheel in the rear of the car. More sidewall, better launch traction.

For road racing/handling: I am going to run a 18" wheel over a 15" wheel less sidewall, better grip for corners.

 

Some vehicles aren't that fortunate.
I couldn't fit a 15" rim over my discs/calipers if my vehicles life depended on it. : ( The 16's I have on there barely fit.

But thats what I would do if I could.

I believe the 300ZX has slightly bigger discs than my car does.

 

ya, I was just giving an example hehe I know you guys are limited with all your fancy brakes I love my 9" rear drums lmao

 

What a "traction patch" is, is the size of the impression the tire would make on the ground. Yes, i was speaking about lateral traction not launch traction. Street tires and drag tires are completely different. Having a stiffer tire in the rear will greatly affect the performance of the car, creating oversteer by reaching its traction threshold well before the front would. Theres always other factors in the suspension that have to be considered as well.

Tire roll as i mentioned is based on the height and strength of the sidewall. Therefore the tire specs that would be needed to match a particular diameter of wheel is in fact very important to handling. No "roll" is actually worse hence the reason a 17" w/ 45 series tire will perform much better then an 18" w/ 40 series.

Not always true, you would have to factor weights of each the tire used vs. the wheel. i.e. a 15" wheel w/ a 205/60-15 tire may actually weigh more then a 17" wheel w/ a 205/45-17 tire.
Wheel weights can vary by a lot ... (i.e. my stock alloy's 15x6 are like 18lbs or so... my new Compomotive's 17x8 are just over 17 lbs)


However, the point at hand is "Why do people do the small/large thing" and i think the general consensus is purely for the looks
yes?

-Dana

 

That is exactally why I put this "Get some good rims that are a good bit lighter than your current rims and your good to go." in there.

 

Yes, i just was pointing out that "a bigger rim/tire" doesnt always mean "more unsprung weight". you can still go bigger and lighter at the same time.

we're saying the same thing i think

 

Yes, I was talking about the rear wheels/rims being a plus size compared to the front wheels.


Thanks for all of the input. Looks like a sparked a good discussion.

 

why dont you just get wider rims in the rear..... 17x9 or something like that

 

The rear wheels are going to be wider anyways (they are wider in stock form too). I was just wondering what's up with the larger sized rear wheels.

 

I got 17s up front and 18s in the back, it works out pretty well for me