I am trying to fit a 255/40/18 on the front on 18x9 wheels and 295/35/18 on the rear with a 18x10 wheel. Does anybody know if they can fit well on a lowered car? I especially would like info on the front tires.
That seems like an awfully big combo to get under the fender. I don't know the 71-73s that well but you also have a '70 and if you compare the clearance room of both that will help. I have a '70 with stock rear springs and 1" lowered front. I run 295/50R15s in back and 235/60R15s in front. I have plenty of room up front so there is some room for larger rubber but you need to compare the overall height/width since you're running larger diameter wheels. In back, my fender lips are rolled and I think I would rub with stock lips so you need to have a smaller overall combo that that, depending upon the differences between '70 and '71 wells.
I don't remember the exact size of the tire but on my previous '71 I was running 14"x9" and I think a 245/50the front and a 15"x10" and a 295/50 in the rear. The fronts definitely rubbed the lower valence if the wheel was turned any sort of angle used in regular driving. The wheels and tires fit under the fenders but they definitely wouldn't tuck inside the fenders.