We mounted a new wheel on the 'Stang to determine the clearance-or lack thereof-of the wider 315 with the inner wheelwell. This is a look at the conflict area-the lip/edge portion of the wheelhousing's rear area. Our 'Stang obviously has rear coilover shocks, but on a stock Fox-body, it's the section just after the shock where the curve to the back of the inner wheelwell begins. The clearance concern is the same on both sides, and it will require a good amount of massaging to achieve an acceptable amount of space for the new tires.
Marking the area to be modified makes things much easier. Use a marking crayon or other bright-colored marking pen. The material below the mark is the stuff that must be eliminated.
Start by using the long-handled, long-head 4-pound sledge. The hanging metal that makes a sharp edge along the inside wheel must be knocked back toward the center of the trunk.
Then, using the top of the same hammer, bump the folded edge upward.
The smaller, 3-pound sledgehammer is then used to tap the folded material against the back side of the wheelwell. This is somewhat of a finesse procedure to make sure the original flow of the wheelwell is retained.
You can almost think of the process as reverse fender rolling. The backside of the inner wheelwell looks similar to an outer lip that has seen the business end of an Eastwood tool.
Although it isn't required, we gave the front portion of the inner wheelwells the same treatment as the rear. This was really just a peace-of-mind move since the front area isn't affected by the width of the 315s.