1972 Buick GS Convertible Tribute 350 cid 15x7 Ralleye Rims 3.73 Posi Tremec TKO 600 5-speed Looking for advice on the best tire size. Thanks for your feedback!
The optional tire for the 70-72 GS was the G60-15 at 26.44" tall. The closest P metric tire is the P245/60R-15 at 26.6" tall. You can fit a P275/60R-15 (28" tall) in the rear, but the 275 tire fits better on an 8" wide rim, 7" is a bit narrow but it will work, just not optimal The taller 275 tire will tame the 3.73 to more like 3.55's.
275R60 really does require an 8" rim. U can run 255R60 on a 7" rim. Running a 275 on a 7" rim causes too much stress on the tire bead ring.
Lots of my fellow Buick club mates have done it for years, but yes, it does require an 8" rim. What happens is the outside edge of the tread gets pulled up a bit on each side. I had a used set of BF Goodrich Drag radials in the 275 size mounted on a 15 X 7. You could look at them after a burnout and clearly see the outside edges of the tread were untouched even though the inflation was proper.
