TheGreenZ28

Hello all!

I have a 1996 LT1 Camaro Z28 that my father and I "restored", you've probably seen him around here (96LT1Z28 or something like that). I recently bought some factory C5 Corvette wheels for it, 18"x9.5" in the back and 17"x8.5" in the front. I read around and multiple people have these wheels and they said they fit fine on their car, but depending on the offset I may need to get spacers. No worries though, not too big a deal

What I am more concerned with is the "correct" tire size. I was planning on getting 285/35-R18s in the back and 255/40-R17s in the front. I've been looking at THIS wheel vs. tire size chart , and it shows that those tire dimensions will fit on those wheels and that they are exactly the right size to get. My question is; are they they "correct" tire sizes for my car/wheel combination? I want to know that I won't be rubbing the tire on anything, especially while turning. Also, I plan on lowering the car an inch, so would these tires allow me to do that?

Sorry, this is probably a dumb question but I want to know exactly what tires to get before I sell my stock-wheel-fitting 245/50-R16s in order to get money to buy new tires.

Thanks for the help!

Nick Terebuch

Injuneer

Stock tires on the 4th Gen V-8's were either:

235/55-16 = 26.1" diameter
or
245/50-16 = 25.7" diameter

The SS and WS6 coupes came with:

275/40-17 = 25.7" diameter

Not aware of any stock tire in 235/45-16 = 24.3" diameter, and Tire Rack does not list any tires in that size.

Since the 275/40-17 was standard on some 4th Gens, as long as you get the wheel offset right (stock SS/WS 17" wheels are 50mm offset) within +/- 5mm, you won't have any problems in the front.

As far as the rear, many of us run the 315/35-17 in the back, and again, with the correct offset (17 x 11.0" 50mm) the problems are minimal... a bit of hammering on the inner fender liners, and cutting the projecting edge off the jounce bumper brackets. The 285/35-18's (25.9" diameter) should not be a problem, as long as the wheel offset is correct.

My list of Corvette wheel specs shows the C5 wheels as 17x8.5" (base) or 17x9.5" (Z06) front and 18x9.5" (base) or 18x10.5" (Z06) in the back. When measuring the wheels, you have to measure the distance between the wheel flanges, where the tire beads sit, not the overall outside width.

See also this site:

Corvette Wheel Offset Calculator • Corvette Central

Note that a 275/40-17 requires at least a 9.0" wide wheel, a 285/35-18 requires at least a 9.5" wide wheel.

TheGreenZ28

Thank you Injuneer. I was at work and I didn't have the right measurements when I posted what I posted. You're right on both points. One, my stock tires are 245/50-R16, and also, I did in fact mean that the corvette rims are 18x9.5 in the back and the fronts are 17x8.5. I was just going by what I had in my head but you're right so thank you.

So, since I was wrong, I assume I should get 245/40-17s on the front, but I can still keep the 285/35-18s on the back. The guy that sold me the wheels had a 98 Z28 and he has 18x11(or something close to that) wheels all the way around with the same offset as these corvette wheels I have and he told me that his fit on just fine and don't rub or anything and his car is also lowered an inch or so. If anything I will buy 1.25" spacers on eBay, they are pretty cheap.

Injuneer

I responded to your PM.

A 245/40-17 is only 24.7" diameter. That's 1" smaller than your stock tire, and will drop the car 1/2" closer to the pavement, and open up the gap between the top of the tread and the fender opening lip by 1/2"

You don't need a 1.25" spacer. That is generally required with the C6 rear wheels, which are 19x10.0" with a 79mm offset (8.56" backspace). Your 18x9.5's have more than 1" smaller backspace.