Originally Posted by Glenn
A 10.5" wheel is not wide enough for a 315 tire. I'm not saying you can't squeeze one on there, it just won't work as well as a smaller tire that fits the wheel properly. A 12" wheel would be more apprpriate for a 315 tire. There just isn't enough room for a 12" wheel on a Mustang without seriously screwing up the scrub radius.
Some 315's are a lot narrowwer than others.
315 on a 10.5" fits better than a 275 on a 9"... so is a 9" too narrow for a 315 as well?
DS used 275 710's pinched on an 8" wheel in FS. Should he have used a narrower tire?
I agree that generally speaking the best wheel for a 315 tire is 12"... but in some cases, it's a different size.
For the front of a 99+ mustang, a 315 tire needs fender work... and resulting offset needs to be less than 6" or the rubbing on the struts will come in to play... for a wider wheel with a 315, you may be able to get away with a little more... for Coilover clearance, you may need a little less.
Scrub radius gets screwed up more and more as the width grows... and the added weight needs to be part of the consideration. For an SLA engineered for the wider wheels, and with mondo fenders, it would do well of course.
My 2 cents...