[Adecco]

I have a 71 GTO with coil overs all aroung, looking to put either a 295/65 DR or 275/65 DR on a 15 x 8 steel rim with poverty caps..

Has anyone done this with no mods.. and what backspace on a 15x8 wheel if you did..

Thanks Tom

[JLMounce]

A 275 section width tire on a 71 A body is pretty easy. There's a decent amount of room back there and for the most part a 0 offset wheel is going to fit nicely back there.

The tubs on those cars will fit a 315 section width tire, but you've then got to start looking closely at the offset to make sure it centers properly.

Considering the cost of most custom offset wheels, it's not smart in my opinion to take somebody's word for what will and will not fit. Once a tire is mounted on the wheel, it's yours, you can't return it.

Measuring for correct offset is pretty easy and you just need a bit of information on how tall and how wide the tire is, then spend 15 to 30 minutes measuring with some straight edges.

Start by measuring both rear wheel tubs to see how much width they have at their narrowest spot (typically between the wheel lip and inner frame rail). Then measure where the mounting pad for the disc or drum you are using sits in relation to the wheel tub. This tells you what your Backspace/offset needs to be in order to center the wheel and tire in the wheel tub. If you're running disc brakes, you need to measure caliper protrusion from the mounting pad. This measurement is to make sure the wheel spokes don't contact the caliper.

Because you're trying to put a 30" wheel and tire combination on the back with that 295/65, I would also measure from the center of the hub to the top of the wheel house. You want to do that with the vehicle's weight on the rear axle. That will give you the static radius available at ride height. You should reduce that by the amount of bump travel the car has. Multiply the number to get what kind of tire circumference you can realistically stick in the wheel house.

Now take all your measurements and decide how much extra room you have inboard and outboard of the sidewall and how much clearance you have from bottoming out the wheel house on the top of the tire. In general you want to see a minimum of a finger width (.5 to 1") between the sidewall and the body work or inner wheel tubs.

Based on the specs I'm seeing online for a few DR's in the 295/65/15 size, I'm fairly certain you're not going to have trouble getting that tire on the rear of a 71 GTO. Most of the width is in the sidewall, not at the tread. If you are running drum brakes, you might be fine with a standard 4" BS / 0 Offset wheel. If you're running discs of some sort, you may need half toe 3/4" more backspace based on my experience with my wife's 71 Chevelle. Those cars handle a 28" in tall tire really well, so I don't really see a huge issue with a 30" tire, unless the car is dropped from stock ride height significantly.

Please do take the time to measure. I've seen people buy wheels thinking they'll fit and spend 4 figures on the package only to have to turn around and sell them at 50 to 60 cents on the dollar brand new because they didn't actually fit.