How wide on rear wheel?

[I_Wanna_Go_Fast]

I have 15x12 Weld alumastars on my 72 with Mickey Thompson 29x15.5x15's.
With the stock wheel tubs they just barely rubbed, Didn't trust it to run it down the track so I sprung for the +4" wheel tubs ($179/pair scratch and dent from jegs), oddly enough they were not scratched or dented. Other than being the wrong color - they were perfect.

After the tubs went on there is more than enough room to tuck the 18.5" wide sportsman's and still have room to party!