I'm setting up a 70 ranchero and I'm trying to figure out rear tire size. I've measured, and a 255/60r17 at 29 inches tall should clear. But I'm afraid that it's too tall. I'll be running 3.73 gears and 4r70w trans. I've done the calculations for rpms at different speeds and the numbers look okay. I don't want to get the tires and mount them up to find that they're too tall or look too big. Does anybody know what size tire works comfortably on this application? Thanks.
Speaking from owning a '71 ... the problem is clearance between the outer tire diameter and the fender well. Your diameter is OK. Generally you must find some tire that has a clearance opposite to the usual method, i.e. built with an offset inside. Take a look at the clearance between the springs and the outside of the tire. That is where clearance must be built into whatever wheels you buy. If you can install your tire, check the clearance as I mentioned above. I'd guess that your size tire is too wide for a stock wheel. Edit .. and I'll just say that there is no way your tire will fit into the space built in where the spare will be mounted. Blame Ford for not figuring that out at design time.
Height-wise it should fit, but, as was said already, wheel offset will determine clearance between springs (inside) and fender edge (outside).
