I just put a set of 15x6 American Racing Torq Thrust II's on my 1963 PV544. I put 205/65/15 tires on and they fit absolutely perfectly. They fill the fenders to perfection yet don't rub in the slightest (I did crimp in the lip on the rear fenders slightly - about 1/4 inch). The car handles much more surefootedly than it did on the skinny 165R15 tires it did have (you could feel them folding over under hard cornering).

These wheels have 3.375 inch backspacing and a 5-on-4.5 inch bolt pattern. This backspacing appears roughly identical to the original rims - meaning the extra 2 inches is all to the outside. However - the steering effort seems to have remained the same.

Old Ford, Chrysler, AMC rims will 'fit' as well - but check that backspacing carefully. Often rims for old domestic sedans stick out a lot farther than you would want. A more modern car with the same bolt pattern is Jeep. The Wranglers and Cherokees at least have 5/4.5 bolt patterns - don't know about the Grand Cherokees.