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How much PSI?

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Old Apr 8, 2008 | 11:39 PM
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Default How much PSI?

The '73 454 I just bought has Goodyear Eagle GT II's. Tire placard on door says to run 20 PSI. That seems pretty low. What do you guys with radials run on your C3's?
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Old Apr 8, 2008 | 11:46 PM
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I have 255 15R60. I put 32 cold and works up to 34 hot.
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Old Apr 8, 2008 | 11:47 PM
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32 Psi
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Old Apr 9, 2008 | 12:05 AM
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Rule of thumb about 1 psi for 100LBS of weight of auto. Your 454 Vette weighs around 3500lbs so 32-35 PSI should get you in the ballpark.
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Old Apr 9, 2008 | 01:35 AM
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Originally Posted by Solid LT1
Rule of thumb about 1 psi for 100LBS of weight of auto. Your 454 Vette weighs around 3500lbs so 32-35 PSI should get you in the ballpark.
Thanks I will Use that rule of thumb
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Old Apr 9, 2008 | 08:32 AM
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What was so different about the OEM radials that such low tire pressure was recommended by GM?
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Old Apr 9, 2008 | 08:42 AM
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Originally Posted by SilverDevil
What was so different about the OEM radials that such low tire pressure was recommended by GM?
In '73 I'm pretty sure that they were coming off the line with bias ply tires. I may be wrong. But that would be a whole different type of tire.
BTW I run 32 psi in my BFG 245's. /:\
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Old Apr 9, 2008 | 09:53 AM
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Originally Posted by 1Sweet66
In '73 I'm pretty sure that they were coming off the line with bias ply tires. I may be wrong. But that would be a whole different type of tire.
BTW I run 32 psi in my BFG 245's. /:\
1973 was the first year for radials on a Corvette.
OEM on my car was option "QRM GR70 x 15 steel belt radial w/s" for $32
(Yes, I have the original window sticker)
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Old Apr 9, 2008 | 10:23 AM
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Biased ply tires ran a little lower, usually 26 to 28 pounds. The 20 pounds on the sticker was so the ride would of been softer.
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Old Apr 9, 2008 | 11:34 AM
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Actually, radial tires ran lower pressures than bias-ply tires. That is because the 'footprint' of an equivalent radial tire had larger area than the bias-ply tire. It is a matter of filling the tire to obtain its designed 'shape' while supporting the car's weight. In general, early U.S. radial tires were underinflated by manufacturer specs, and early radial tire failures proved that out. Proper tire pressure should be in the 28-32 psi range. Lower pressure will yield a softer ride; higher pressure will yield better stability [but firmer ride and less tire life].
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