In restoration process now is time for tires, please let me know what was the original 1974 Buick Century Gran sport stage1 tire size from witch tire brand and what is closest new modern tire size to the original ones?
Optional Tire was a GR78-15. It was 27.52" in height with a section width of 8.15".
I would go with a P225/70R-15. It is 27.40" tall with a section width of 8.85"
I recommend the Cooper Cobra Radial. I have these on my 70 GS455 Stage1. They ride and handle really nice.
1970 GS455 Stage1 Race weight 4025 lbs.
TSP 470, 602 HP, 589 TQ
MT headers, Gear Vendors Overdrive
Best E.T. 11.54 Best MPH, 116.06
1998 Riviera SC3800