Tire pressure.....
Thread Starter
Melting Slicks
Joined: Feb 2011
Posts: 2,840
Likes: 65
From: Tree City
Tire pressure.....
Tuesday, 2 days ago I had new tires put on my 78 Corvette. While they were putting them on they asked me how much pressure I wanted in the tires. I said I usually put about 32 lbs. In them. They looked on the side door panel it said, cold tires-- 20 lbs. in the front and 26 lbs. in the rear.
Really??
🤔
Really??
🤔
Instructor
Joined: Dec 2020
Posts: 246
Likes: 165
Hello Jim, I have a '78 also. There are two listings for tire pressure on that label, "maximum load," 28 front and 32 rear. Then there is "reduced load" 20 front and 26 rear. I run 28 in all 4. Regards, LowSporty
2026 Loser of the Year
Joined: Sep 2013
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From: New Or-leens Loo-z-anna
Vettes aren't heavy cars so I run less air pressure.
Since the rear of the car is much lighter I run 30psi in front and 28 in rear tires around town for a smoother ride.
On open roads I run 32/30.
Everyone does what suits their driving style/firmness.
Since the rear of the car is much lighter I run 30psi in front and 28 in rear tires around town for a smoother ride.
On open roads I run 32/30.
Everyone does what suits their driving style/firmness.
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And it really depends a lot on the tires your running.
No one is running factory tires anymore. So the sticker on the door is totally useless.
I've been running 255/60-15's for over 30 years. Cooper's.
And have had very good tire wear running 32PSI all around.
Now I'm certain that the door sticker that is long gone on my car wouldn't agree with that.
But I know what works.
No one is running factory tires anymore. So the sticker on the door is totally useless.
I've been running 255/60-15's for over 30 years. Cooper's.
And have had very good tire wear running 32PSI all around.
Now I'm certain that the door sticker that is long gone on my car wouldn't agree with that.
But I know what works.
Race Director
Joined: Oct 2000
Posts: 12,687
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From: Shamong, NJ
Radials were still fairly new to US automakers and drivers in the 70's. Because of that, GM tended to recommend lower pressures then we've become accustomed to on modern cars. Also back then makers were more concerned with ride, then they were with gas mileage or handling.
Strangely, GM set the pressures lower for the Corvette, than just about any other GM car. I've had a 74 Trans Am and a 74 Corvette, and the OEM tire for both was a GR70x15 (same as the current metric size P225/70R15). The recommended pressures for the TA was 25 front and 24 rear (normal load), and 25 and 28 (max load). In comparison, GM recommended 20 front and rear for the 74 Corvette under all conditions. I'm sure part of that was due to the Trans Am being about 350 pounds heavier, but 20 pounds is still awful low, even the TA's 25/24 seems low to me. It didn't take long for GM to start raising the recommended pressures though, as my 81 Corvette has recommended pressures of 35 front and rear, under all loads.
I did a lot of autocrossing years ago, so I got use to higher pressures, and leaned I preferred my tires to have a stiffer sidewall, and less sidewall flex, so I've always run pressures in the 32-35 pound range on all my cars. But that's just my personal preference.
Strangely, GM set the pressures lower for the Corvette, than just about any other GM car. I've had a 74 Trans Am and a 74 Corvette, and the OEM tire for both was a GR70x15 (same as the current metric size P225/70R15). The recommended pressures for the TA was 25 front and 24 rear (normal load), and 25 and 28 (max load). In comparison, GM recommended 20 front and rear for the 74 Corvette under all conditions. I'm sure part of that was due to the Trans Am being about 350 pounds heavier, but 20 pounds is still awful low, even the TA's 25/24 seems low to me. It didn't take long for GM to start raising the recommended pressures though, as my 81 Corvette has recommended pressures of 35 front and rear, under all loads.
I did a lot of autocrossing years ago, so I got use to higher pressures, and leaned I preferred my tires to have a stiffer sidewall, and less sidewall flex, so I've always run pressures in the 32-35 pound range on all my cars. But that's just my personal preference.
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