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I have a 1972 and a1976 C3. Recommended pressure for 72 is 24f 24r. For 76 it is 20f 24r. Am I correct in my understanding that the difference is due to the factory change from bias to radial tires during this period? And since I have converted the 72 to radials should I now follow the pressure recommendations for the 76 (20-24) on the 72? Appreciate all input.
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
back in the day at my service station, the owner had me putting inn 32 all the way around...bias ply and radial unless the manufacturer had different posted on the sidewall. The 1982 specs was 35/35psi with radials....I personally would start at 32psi, or see what the tire calls for on the sidewall and go up or down from there and see how it handles..
The factory specification is for the original tires. Now long gone. And for ride quality, not tire life or handling.
I run 32 all around on my 77. Have for many years. I've never worn out a tire. I replace them when they get old. They always wear perfectly. No edge wear. No center wear.
It also depends on the tire brands. Some have stiffer sidewalls, etc.
As said above, too high pressure will give a hard ride, and too low will give a soft, squishy ride.
Both will give unequal tread wear.
I would start at 30# cold--just a good round #--and adjust from there. Too low pressure can be unsafe at freeway speeds, so error up.
With my 255/60/15 Coopers on my '69 BB, I run 28 front because of the heavy front end, and 26 rear.
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Originally Posted by 4-vettes
The factory specification is for the original tires. Now long gone. And for ride quality, not tire life or handling.
Remember also that by '76 it was more about touring than performance. Lower pressure/smoother ride.
Plus this was early in the radial tire days and they were still figuring things out.
I've been running 28 front 32 rear cold in my 255/60s for years now...
Yes, but... they also state a weight along with that psi, like 45psi @3200 pounds**. A typical C3 is going to be about 750 pounds at each tire, so there's no risk of over-pressurizing the tire as long as the weight rating is above the actual. For my cars, I run about 32 all around for general driving but in the old days of auto-crossing I over-inflated, just for the event, to something like 45 so the sidewalls were stiffer. Modern tires are very forgiving of pressures with some guidelines: lower pressure equals softer ride but more heat build-up and increased edge tread wear; higher pressure equals harder ride with less heat but increased center tread wear.
** I may be wrong about that -- the Hankook tires on my '67 do not have a psi@lb statement. They state max pressure and on a second line max weight. I haven't checked the other cars' tires...
Last edited by barkingrats; Jun 3, 2023 at 10:12 PM.
Did anyone look at the title of this thread and think about that "too broke to retire" guy that used to be on here. He was always saying to run 20 lbs of pressure in tires. He did provide some good entertainment.
I used to run 20..i just upped them 2 psi 22/28 COLD so i don’t go below. I like the ride and no odd wear at all.
I put about 4-5000 miles a year and bet the tires still age out before any wear..
i wonder if the epa fuel ratings were the 30/35..
Depends on the "Ride" you prefer:
Over 32 psi = Go Cart Ride/Fast curves.
Under 28 psi = Slow down on the curves/Squirmy ride.
Choose which you prefer
I agree. A little experimentation will help you decide. The nice thing is it won’t cost anything to experiment.
My personal preference is 30-32 cold. As I want to see 36-38 on track. Tires have different characteristics. So what works good for a B.F. Goodrich tire may not work as well for Michelin.
I agree. A little experimentation will help you decide. The nice thing is it won’t cost anything to experiment.
Experimentation, YES. I just inflated my Hankook Optimo set to 35psi. They were at ~30 but felt kinda Jello-y on curving roads. At 35 they lost that undesirable characteristic altogether and feel good to me now. My previous set of Michelins had been fine at lower psi but not these.
tire pressure question
Remember also that by '76 it was more about touring than performance. Lower pressure/smoother ride.
He did provide some good entertainment.
