[69fastback]

What backspacing do I need to use for a 15X8 wheel, to run the widest tire possible? Something comparable to a 275/60?

[460brevill]

i went to the american tire catalog and called them,told them the rim i wanted and the size tire i wanted.next day they were in my shop.perfect fit.

[MustangOne]

You can go to a 9" rim I run a 9.5" rim on the back of my 1965 it has a 5.5 Back on it.

So a 9" I would go with a 5" back spacing.

[69fastback]

Originally Posted by MustangOne You can go to a 9" rim I run a 9.5" rim on the back of my 1965 it has a 5.5 Back on it. So a 9" I would go with a 5" back spacing.

Can you run something as big as a 275 without it rubbing the springs? and without rolling the fenders or anything....

[460brevill]

i am running a 275 50 15 now.

[MustangOne]

Originally Posted by 69fastback Can you run something as big as a 275 without it rubbing the springs? and without rolling the fenders or anything....

on yours I do belive you can. With my wheels on the 1965 clear the leaf springs by 1/4 of inch. and go up into the wheel wells.

Im Running a 245/45/17 with 9.5" rims

[69fastback]

Originally Posted by MustangOne on yours I do belive you can. With my wheels on the 1965 clear the leaf springs by 1/4 of inch. and go up into the wheel wells. Im Running a 245/45/17 with 9.5" rims

There's pretty good clearance now with the 275/60s that are on it, between the tire and leafs. They used to rub the fenders on big bumps, but since the Caltracs, they don't rub anymore. I guess the rear end just stays located better. I tired to measure the backspace but I'm not too sure with them on the car. They almost look like a 5" backspace, and I'm pretty sure they're an 8" wheel.

I know the 69-70s have better clearance in the back, but I don't want to fork out a bunch of cash for prostars and ET streets, and then have them not fit.