If you are worried about power, get the turbo, do an engine swap, or lower geared tranny/differential. I have seen rubicons w/ 35's have a top speed of 65 with stock gears. I know I can do alot with 31" tires and skid plates from experience, 33 and 35's will do the hardcore stuff, I have done hairy stuff with 30's too. If I get a turbo, or regear to 4:56 I will get 31's or the interco 32x10.50x15's and stop there. Too much meat on the tires takes away the power fast. Aluminum rims are not as strong as steel, but i have done some hillacious stuff on them without problems other than scratches, and aluminum gives back alot of power lost to turning those steelies. Steelies take alot to get to momentum speed, and keep the momentum going better than aluminum do, but I am unsure if it is enough to matter. I noticed a big difference switching to aluminum rims though.