What backspacing and width of 15" wheels will fit reasonably on 4th gens? I plan getting a set of Welds and wanted to know what fits and what width tire would fit with minimal banging/grinding.

I plan on running a minmum of an 11" wide slick.

 

If you are looking at 15" Welds, can we assume its the Draglites or Pro-Stars?

If so, for the back, you need either 15x8 5.5" or 6.5" backspace, or 15x10 7.5" backspace. The 15x10's offer the advantage of fitting just about any slick you could fit on a 4th Gen.

Once you select the size, you need to address the interference between the center disc of the Weld wheel and the rear brake caliper cooling fins. The fins need to be ground down on the corner of the caliper. Then you need to address the stud length issue. The stock studs may not meet the NHRA requirement that the threads engage at least 1/2" in the HEX portion of the lug nut. The Welds use an "extra long shank mag-style" lug, and they will not give you any credit for the portion of the thread that engages in the "shank" portion of the nut. I don't know exactly how bad the stockers are, but I had 2" studs on my Strange 12-bolt, and had to swap them out for 3" studs.

In the front, are you looking at a real "drag" skinny for the track, or just a narrower wheel that will allow you to mount a radial for street driving? The 15x3.5" 1.75" backspace "skinny" is marked "track use only". In any case, the front wheel requires a 5/16" spacer to push the wheel out to clear the spring clips on the brake pads and the big horizontal arm on the steering knuckle that supports the calipers. And you need the longer studs. LPE, GMPP and ARP make longer replacements.

Click on "Trailer Queen......" in my signature for the end results.

 

Thanks for an excellent explaination as always Fred, you got me going in the right direction.