Originally Posted by OldSub
Frame width is 46 inches. Two 14 inch wide tires is 28 inches. Total width with no clearance would then be 74 inches, which is the approximate width across the fenders on one of these trucks. You can't run 14 inch wide tires without modifying the frame, the fenders, or lifting the truck. Or maybe some combination of all three.

If you run 12 inch wide tires you could run about 1 inch clearance between frame and tire, tire and fender. That should be enough, and would still require a slight tub to keep the tires under the fender at stock or lower height without rubbing anything.

If you assume 12 inch wheels to support those tires, add an inch on each side for clearance, and put the mounting surface at its ideal centered position in the wheel, you then can add 46 (frame width) plus 2 x 6 (half of each wheel) plus 2 x 1 (frame clearance on both sides) to arrive at your ideal axle width. 46 + 12 + 2 gives you 60 inches.

Armed with that information you now know you either need a 60 inch wide rear, or your wheels will have negative offset to fit 12 inch tires in the fender. If you go wider than 12 inch tires, you have some new issues to deal with, possibly modifying the frame or fender.

I believe the best approach is to measure at least six or eight times before cutting or buying...

thanks,that helps

1950 custom streetrod build
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71 corvette conv, 525 hp big block