Fitting some 285's on my Z

[benhart21]

I just picked up some C5(replica) rims today, 17x8.5 front(I think) and 18x10(supposedly, don't know the backspacing yet) for the rear. Went to put them on and the fronts fit fine with a 255/40/17 on them, but the rears 285/40/18 are hitting the bump stops. My buddy that I bought them from threw in the spacers he used to fit them on his Formula, and they fit with the spacers, but then the studs are too short. Anyone know a good quality spacer/adapter? I don't wanna just add longer studs, but my car looks goofy with two different sets of rims on it.

edit: It's a 95 Z28

[Injuneer]

First, find the backspace of the wheel. I suspect it is close to 8.0", and that's enough to cause problems with the edge of the wheel catching on the jounce bumper bracket as you jack the car, and for the inside edge of the tires to rub on the inner fender liner.

Those of us with the 17x11 ZR1 replicas with 7.93" backspace face the same problem. The edge of the jounce bumper bracket can but cut off to solve that problem, and the inner fender liners can be hammered to add clearance. Bur that's an 11" wheel, and your 10" wheel (if that's what it is.... most 'vette wheels are x.5) will look sunk in the wheel well.

The best adapters I have seen are made by Skulte Performance Designs:

http://www.skulte.com/

Then you may need to rethink the tire size selection. You picked tire sizes that will have the rear tires almost 2" larger in diameter than the front ones. Maybe that's the "look" you want, but just so you understand what you have done:

255/40-17 = 25.0" diameter. That's .65" smaller in diameter than the stock (if you had the Z-rated option) 245/50-16 tires that came on the car. That lowers the ride height/ground clearance 0.33", and opens up the gap between the top of the tire and the fender.

285/40-18 = 27.0" diameter. That's 1.35" larger in diameter than the stockers. That raises the back of the car .65" and now you have a 1" "rake"... again, if you want the car to have a rake, this is one way to do it.

[benhart21]

Finally got around to measuring and all that, and it's an 18x10.5 I wasn't too sure how exact my measurements would be for the backspacing, so I looked it up online and it's +56mm/7.95" I had the fenders rolled all the way around to make room for it just in case this situation presented itself. Now I just need to find an appropriate spacer to make everything line up, as I'd rather not remove the jounce bumpers.

When it comes to the tire size, I didn't have a choice with what was mounted on them right now, since they're second-hand rims. They just so happened to have the 285's on them(Toyo Proxes T1-S). For $500 with all 4 rims and tires, I couldn't complain since replicawheels.com sells them for $260 a wheel(on sale for $208 right now). I'm not a fan of the raked look, and when I replace the tires soon, I was thinking of scaling back to a 275 with probably a 40 series sidewall still. I think a 35 series would be a little too small of a sidewall for me, in the interest of comfort.