Wheel/Tire selection help please ?

I've got 275 60 15 m/t's drag radials mounted on factory rallye wheels which are 15x7 4" bolt pattern,on my '70 duster with everything still in the stock locations,they fit and look great..

That sounds good, got any pictures by chance ?? I've got 14" stock rallyes but wanna go to 15" rims..

Just a quick question.. Today I measured the distance center to center on the axle studs, and it's more like 3 3/4" .. I'm guessing that counts for 4" small pattern??

Thanks,

Kenny