i have a 98 z28 with draglites 15x3 on front and 15x8 in rear with a 275/60r15
mt et streets the rear tires rub on inner fenderwell what other tire size option do i have i also think tires look to big for rear any pics would help

 

What's the backspace on the 15x8" Draglite? Typically you would use a 5.5" BS, and that should leave the inner edge of the tire about 1.5-2" from the inner fender liner. Where is the tire rubbing..... sidewall or tread? The fact that its a 28" tire isn't helping. Do you need a 28" tire, or could you work with a 26" or 27" tire?

 

im not sure what the backspacing is but i had to grind on caliper for them to fit
they rub on the very top of the sidewall i don't have to have a 28'' tire but i don't know how a 26 0r 27'' tire would look or what size that would come out to
if you know that a 26 or 27 tire would look good let me know

 

the sidewall is probably rubbing the inner wheel well right above the lower control arm. it can be fixed with a hammer. doesnt take much, just a few whacks that no one will ever see.

 

Grinding the caliper fins has nothing to do with the backspace.... the interference with the caliper fins is on the center disc.

If you get a wheel with the correct backspace, it should not rub. I have a 15x10" wheel with a 7.5" BS, and 28x11.5-15 QTP's and all it took was a bit of hammering on the inner fender liners. With a 5.5" BS 15x8" wheel, you would have 2" more clearance from the inside edge of the wheel to the inner fender liner than I have.
It doesn't sound like the problem is the tire diameter. Sounds like you have too much backspace.