My 67rs originally came with the 14" wheels and was switched over to 15" Goodyears on the rallys before I took possession. The 14 inch tires were 24 psi cold. Should I be running the 15" tires at 24psi also?
Sorry. Yes, Bf Goodrich. It says on the sidewall maximum psi is 32. I just assumed like any other car, 32 would be after driving around for a while, so I would need to start at a lower pressure. Thanks.
I'll add the following to what has been posted above, whatever tire pressure you decide to run, the important thing to watch for is the tire wear area. If the outside edges of the tire tread are wearing faster than the center of the tread, the tire pressure is too low (at least it's too low for optimal tread wear) and should be increased. If the opposite is occurring (the center of the tread is wearing faster), the pressure is too high and should be reduced. The width of the tire tread contact area and the weight on each tire effects tread wear as does the width of the rim the tire is mounted on. In the front of the car, the toe in and camber settings also effect tire wear in addition to handling. As with most things in life, it's all a compromise
The tire pressure on the sidewall is "max cold pressure" and would be recommended only when loading the car up with a lot of weight. Piney you are right that once driven the tire pressure will increase and it's ok that the pressure hot is over the max.
In a modern vehicle, run the auto manufactures recommended inflation pressure and adjust by a couple lbs up or down for your driving conditions (long hwy drives, heavy loads etc) but don't exceed tires cold max limit.
Our old classics are a different story unless running the same type of tires the car was sold with. The important thing is not to exceed the cold max rating and the only reason to run the cold max rating is if you have 4 passengers in the car and a couple bags of cement in the trunk.
Scott's got the right idea about watching tire wear but that will take you some time before visible signs of wear occur. I would start out in the 26 - 28 psi cold range and never adjust the pressure once you have driven and warmed the tires up. Also watch out for a car parked outside where one side is in the sun and the other is in the shade. Even if you haven't driven the car all day the tires in the sun could be a couple lbs higher than the ones in the shade.
In the mid 70's when I was mounting tires we figured 7 LBs per ply. 4 plys like the E70-14 and the GR60 15's got 28 PSI. 10 ply truck tires got 70. You'll be good with 28 PSI in those old school T/A's.
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