A very popular wheel is the 15X7" Rally II, it's probably used by enthusiasts on more late '60s and early '70s Pontiacs than any other factory wheel.
This was my '70 T-37, it now belongs to PY member 'goatless' (Jeremy) in CT. It has 'real' Pontiac 15X7 Rally IIs with 4.5" backspace, running 245/60s up front and 275/60s in the back. Tires up front were Remingtons, out back they were some other cheap generic brand tire.
Up front the 245s are about as big as you can go without rubbing issues. The 275s in the rear would be a better fit on a wider 8" wheel, but look just fine and handle pretty well on the 7" wheel (which is one of the recommended rim widths for this tire). Suspension and rear axle width is completely stock, including the original saggy springs.
