Correct Tire Pressure...
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Melting Slicks
Joined: Feb 1999
Posts: 2,473
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From: New Paltz, New York USA
Correct Tire Pressure...
can someone tell what the correct tire pressure is on my 81? I know there is a sticker on the drivers side door, but its so faded I cannot read the numbers. I just had new tires put on and want to make sure the pressure is right. Thanks.
Race Director
Joined: Oct 2000
Posts: 12,682
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From: Shamong, NJ
There wasn't a standard tire pressure for 81 Corvettes. The recommended pressure varied by car, based on tire size (225/70 or 255/60), and optional equipment.
I do agree that 32 lb cold, is probably a good balance between ride and handling. I normally run 35 pounds in all of my cars, but I prefer a tire that has a quick response vs a softer ride.
Race Director
Joined: Oct 2000
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From: Shamong, NJ
I would never run pressures that low.
GM first started using radials in 73, and they were still trying to come to terms with them in the mid 70's. Corvettes were also transitioning from a performance car, to more of a touring/luxury car. They were recommending low pressures at the time, to improve the harsh ride normally associated with both Corvettes and radials.
GM first started using radials in 73, and they were still trying to come to terms with them in the mid 70's. Corvettes were also transitioning from a performance car, to more of a touring/luxury car. They were recommending low pressures at the time, to improve the harsh ride normally associated with both Corvettes and radials.
Melting Slicks
Joined: Apr 2009
Posts: 2,632
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From: Great Plains Iowa
I have always run 24 psi in the front and 20 psi in the rear of my big block '71 and the tread wear is perfectly even. Pressures near 30 psi will quickly destroy the tires because the centers will wear out 3 times faster.
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Burning Brakes
Joined: Apr 2008
Posts: 1,222
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From: shelbyville West Michigan
what do the tires say? that is what I generally go by, not outdated specs for tires that are no longer produced.
I used to go by the standard 34 psi all around until the last 10 yrs. or so. I've noted a lot of new tires, especially lower profile, need 50...even modern replacements with newer compounds need more pressure than the old ones in the same size.
I used to go by the standard 34 psi all around until the last 10 yrs. or so. I've noted a lot of new tires, especially lower profile, need 50...even modern replacements with newer compounds need more pressure than the old ones in the same size.
Advanced
Joined: Oct 2014
Posts: 55
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From: Woodland Park CO
If you value the fillings in your teeth (and your cars suspension) - never set by what's on the tire. What's on the tire is a maximum that the particular size will hold maximum weight. I'm in the tire industry going on more than 45 years - currently with Cooper Tire Co. Tire manufacturers will always say what is established by the automobile manufacturer. When I was with Pirelli we said + or - 10%. My 255/60R15 Cobras are running +10% @ 22F & 28R. That tire at 20psi has a load index of 1,453 each so just the fronts together would support 2,900 lbs. . Those recommended pressures have as much to do with oversteer and understeer along with handling the weight and forces of driving.
Race Director
Joined: Oct 2000
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From: Shamong, NJ
My car is fairly loaded. Besides the standard AC, power steering, brakes and windows, it also came with cruise, am/fm cassette, glass tops, power seat, p/mirrors, p/locks, aluminum wheels and the optional P255/60R15's.
Thread Starter
Melting Slicks
Joined: Feb 1999
Posts: 2,473
Likes: 10
From: New Paltz, New York USA
If you value the fillings in your teeth (and your cars suspension) - never set by what's on the tire. What's on the tire is a maximum that the particular size will hold maximum weight. I'm in the tire industry going on more than 45 years - currently with Cooper Tire Co. Tire manufacturers will always say what is established by the automobile manufacturer. When I was with Pirelli we said + or - 10%. My 255/60R15 Cobras are running +10% @ 22F & 28R. That tire at 20psi has a load index of 1,453 each so just the fronts together would support 2,900 lbs. . Those recommended pressures have as much to do with oversteer and understeer along with handling the weight and forces of driving.
Thanks, that is some cool information. Yes, I have 4 new Cooper Corbra 255/60R 15 on the vette. I am not going out and setting my tires @ 22F & 28R. Thank you very much.
Advanced
Joined: Oct 2014
Posts: 55
Likes: 1
From: Woodland Park CO
Richard, My car is a 78 so the recommended pressure is different than your 81. Here's what I found on yours:
1981 Tire and Wheels
Standard Tire size--P225/70R15
Type--Steel Belted Radial"
Inflation Pressure (cold) front--35 PSI rear---35 PSI
Revolutions per mile--(45 MPH)--760
Standard Wheel--Short spoke spider, steel rim--15x8
Wheel Offset= -0.50"
Optional Tire--Good Year Eagle GT"
Size--P255/60R15
Type-- Steel Belted Radial
Optional Wheel--Cast Aluminum
Rim Size--15x8
Wheel Offset= -0.50"
I don't know if GM made any significant changes to the suspension in those 3 years or if it was mostly fuel ratings being improved by increasing the pressure. If I was you, I would go + or - 10%. Reduce for a smoother ride cruising or increase for stiffer ride if your a hard driver or on the track. As some stated earlier, you can experiment some too within reason. Ultimately you can judge by the tire wear with even being optimal. Too low and you'll wear the shoulders, too high and you'll wear the centers.
Hope I haven't confused you... Jay
1981 Tire and Wheels
Standard Tire size--P225/70R15
Type--Steel Belted Radial"
Inflation Pressure (cold) front--35 PSI rear---35 PSI
Revolutions per mile--(45 MPH)--760
Standard Wheel--Short spoke spider, steel rim--15x8
Wheel Offset= -0.50"
Optional Tire--Good Year Eagle GT"
Size--P255/60R15
Type-- Steel Belted Radial
Optional Wheel--Cast Aluminum
Rim Size--15x8
Wheel Offset= -0.50"
I don't know if GM made any significant changes to the suspension in those 3 years or if it was mostly fuel ratings being improved by increasing the pressure. If I was you, I would go + or - 10%. Reduce for a smoother ride cruising or increase for stiffer ride if your a hard driver or on the track. As some stated earlier, you can experiment some too within reason. Ultimately you can judge by the tire wear with even being optimal. Too low and you'll wear the shoulders, too high and you'll wear the centers.
Hope I haven't confused you... Jay