17in fr 18in rear wheels

[ModsAway]

I believe the Zo6 comes from the factory with 17 wheels on the front and 18 inch wheels in the back?

Why is it that they do this and can i do the same?

I am replacing my rear wheels with 10.5in wide rims and 315 GS-D3's and want to avoid the use of wheel spacers. One way I have heard of this done is by lowering the car and then the IRS bolt is inside the wheel instead of rubbing the tire.

I am lowering my car but likely with something like Eibach for a less drastic drop so was wondering the benefits of 18inch wheels and if this would help me out.

All suggestions appreciated, lets hear em.

 

[500hp03Cobra]

Its mainly for appearance.

 

[ModsAway]

Think it would help me clear the IRS bolt or will I be fine with the 17's and lowered slightly ??

Any opinions?

 

[hmwave]

Not sure about the clearance with 18" but it's true the IRS bolts clear the wheels/tires with the suspension loaded in most all cases.

The case where it DOESN'T is the one where you are travelling at high speed and lift the rear end off the road over a hump.
If you are lucky your tires will still have enough inside sidewall not to both blow out when you land. At high speed.

Granted you won't do it often because if you ever do, it might be the last time you do anything.

Not worth the risk IMHO.
My bolts are ground and the edges rounded off just to make sure.

 

[akaeric]

I just went with stock 2004 chrome SVT Cobra wheels except the backs are 17x 10 1/2 with 315's and I used Billit 1 inch wheel adapter and it worked out great. The wider stance handles better. If your planning to lower the car the adapter wouldn't work it the fender would rub or be real close to it. Maybe lowering is your way to go if your going to do it anyway. I didn't have to grind any studs. I put it through the test I smoked the hell out of them and pulled the wheels and checked the adapters and retorqued them no problem.

http://www.wheeladapter.com/wheel_adapters_and_wheel_spacers.asp

 

[hmwave]

Here's my deal FWIW...

315/35/17 GS-D3's on 10.5 17" Replica Rims (Discount Tire Direct) with the SVT centers (wheels $200 each).
I have a 3/8" hub centric custom made aluminum spacer ($100), MM IRS bushings ($60, a real bitch to fit!!!), aluminum pumpkin bushings ($80, a pain to fit), 00R Cobra R shocks ($260, not too bad to fit), 14mm front IRS bolts ($15), Eibach Pro springs ($260, drop the IRS to fit) with MM urethane insulators ($80 I think), and AFS extended tip lug nuts ($70, and very important that you have at least 12 full threads on each lug nut for this combination, or you can fit Steeda extended studs though that's much more work).

I purchased new 12mm upper IRS bolts from the dealer ($20) and ground them myself on a wheel carefully rounding the tops to around 1/8" to make sure there was a nice smooth surface should the tire ever come into contact at any speed.
Jacked I have around 1/8" clearance between the inner tire wall and the bolt head.
I've yet to get it all aligned - sometime in the next two weeks I expect.

Everything fits well and I have around a 1.5" gap between the rear tire and the fender. Just came back from an SVTOA show at the weekend and many folks commented that my car looked "just right" with that setup.
I have the front Eibach's too and the front fender spacing is low but I haven't grounded out yet even with spirited cornering.
The car has a slight rake to it now.

Hope that helps.

 

[03InThe11s]

i have no problems with my 10.5 afs and 315/35/17 bfg's. but my car is pretty much slamed on the ground. my tires have come in contact with the fender once, but i had 7 people cramed in my car (long story) if i did have problems with the bolt i would grind the bolt down and use a small 1/4" or 3/16" spacer. that would take care of it.

 

[Dave99GT]

Originally posted by hmwave
Here's my deal FWIW...

315/35/17 GS-D3's on 10.5 17" Replica Rims (Discount Tire Direct) with the SVT centers (wheels $200 each).
I have a 3/8" hub centric custom made aluminum spacer ($100), MM IRS bushings ($60, a real bitch to fit!!!), aluminum pumpkin bushings ($80, a pain to fit), 00R Cobra R shocks ($260, not too bad to fit), 14mm front IRS bolts ($15), Eibach Pro springs ($260, drop the IRS to fit) with MM urethane insulators ($80 I think), and AFS extended tip lug nuts ($70, and very important that you have at least 12 full threads on each lug nut for this combination, or you can fit Steeda extended studs though that's much more work).

I purchased new 12mm upper IRS bolts from the dealer ($20) and ground them myself on a wheel carefully rounding the tops to around 1/8" to make sure there was a nice smooth surface should the tire ever come into contact at any speed.
Jacked I have around 1/8" clearance between the inner tire wall and the bolt head.
I've yet to get it all aligned - sometime in the next two weeks I expect.

Everything fits well and I have around a 1.5" gap between the rear tire and the fender. Just came back from an SVTOA show at the weekend and many folks commented that my car looked "just right" with that setup.
I have the front Eibach's too and the front fender spacing is low but I haven't grounded out yet even with spirited cornering.
The car has a slight rake to it now.

Hope that helps.

WOW. $1345 before the tires. Guessing the tires were $200 each (probably a low guess), for a total of $1,745. It really adds up fast!

 

[hmwave]

I did pretty much all the rear end mods to help eliminate wheel hop.

You could get by with just rims and tires and the spacers/lug nuts if you are on a budget.

If you choose 315 Nittos you can use the stock rims.