My 1994 Coupe came with 17" Wheels, 8.5" front and 9.5" rear. The Offset was 56mm for both. Looking through old archives I see AR used to make Thrust and Thrust II wheels with a 56MM offset for my car. These are only special order now and the backspace is listed at 45MM offset. Is this right? Does it make a difference? Is there a range of offsets I can be looking at that will fit properly (besides asthetics) that will fit inside my wheel wells without protruding. Thanks for the feedback, I just dont know much about offsets on wheels.

 

IIRC, American Racing made the Torque-Thrust II in custom offsets. You could order the wheels with just about any offset.

There is a difference in how backspacing and offset are measured. The backspacing is the distance from the wheel mounting flange to the inside edge of the wheel. The offset measurement is the distance between the mounting flange and the centerline of the wheel rim.

The 45mm offset you are considering is 11mm shorter (or about 7/16") than the C4 wheel offset. This would cause the wheel to sit that much further out compared to the Vette wheel. If you went with 4 wheels that were 17x9.5", you could use a 275/40-17 tire on all 4 corners and not have any issues. You can also rotate the tires for better tire wear.

One thing you also need to check is whether or not the T-T2 wheel will clear the C5 caliper. If it doesn't, you would have to use spacers to extend the wheel further outward to gain any necessary clearance.

 

You haven't mentioned the "width" of the wheel! Everything is relative when you're doing "tire/wheel" combinations. Post the complete specs for the wheel you're contemplating.

I didn't see C5 brakes mentioned anywhere in your post, If there are any brake modifications they certainly need to be taken into consideration. Tire/wheel fit-ment is "car to car" - there's no "cut & dried" - you'll like these! Make sure you understand - it's not my money or Joe's, John's or Jim's - you're the guy that will have the stack of tires/wheels in the corner!

 

Width I am looking at is 9.5". I can special order the 45mm offset and I found a set of the 56mm offset at a local shop. I have stock C4 brakes.

 

You could use a plumb-bob and drop it from the quarter lip of the rear and measure 11mm from your tire sidewall towards the plumb-bob and that's where the tire on the 45mm offset would set. Move one of the rears to the front and duplicate that with the plumb-bob and see what you think.

You can confirm the offset of the "locals" by measuring the back-spacing. Depending on the wheel flange width you should have a back-spacing dimension of 7.4" +/- maybe .10

Apparently the 45mm special order wheels are less expensive or there would be no questions.

Some might actually prefer the 11mm "push" towards the quarter/hood lip for appearance reasons. It would certainly "fill" the wheel-house.

I don't know that stock wheel studs are long enough but if they were you could stack 11mm of washers on three studs and mount your present 9.5's to check the fit. DO NOT DRIVE but you could confirm the appearance on your car using your 2 9.5's on one side of the car.

If you opt for the 45's get in writing before you order the wheel specs confirming both the offset and maybe the back-spacing, that would/should cover you if they were something other than that dimensionally when you receive them. When you receive them check them before mounting tires! Back-spacing would be 7.0 +/-

I believe "c4cruiser" might have been cautioning you regarding possible future "upgrades" for brakes. It might be something to consider if you ever thought about it! You would have no issues with a J55 front brake package.