Quote:
Originally Posted by CapriRacer
Back then, car manufacturers tended to use minimal sized tires. That would be a good
starting point, since in the many years since, they've increased the tire sizes.
So a 1960 to 1963 Chevrolet Corvair came with 6.50-13 inflated to 15 psi front/
26 psi rear - except for the wagon (They made a Corvair wagon?) which was
7.00-13 inflated to 15/28psi.
Let's ignore the wagon.
The load carrying capacity of a 6.50-13 at 15/26 psi is ..... well it's a bit tricky. The
load tables from the 1960 Tire and Rim Association yearbook only go down to 20 psi.
The value at 26 psi is 875#. If I extrapolate down to 15 psi, I get 650#.
And an important consideration is rim width = 5.5.
So allow me to do the math. If we chose a 13" tire from today's offerings, the closest
thing is a P155/80R13, but it is 1 3/4" smaller in diameter and requires 3 more psi to
carry the same load. But Tire Rack only lists 2 tires available in that size.
A P175/70R13 has more offerings (4), suffers from the same diameter problem, but it
has more width and might rub, and doesn't require more pressure to carry the same load.
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Hey there! We were just yacking it up on Car Talk direct messager!
See, all I want to do is establish a baseline, 'rule of thumb', or recommendation for cold tire pressures for owners of Corvair 1.0 who decide to convert from bia-ply to radial tires on those vehicles.
Of course it will involve maintaining the historical front-rear cold pressure offset, as you mentioned earlier F:15 R:26psi.
I've heard stories of 1.0 drivers putting in anywhere from 30 to 35psi in
all four tires, pressures which I suspect are, for one, too high overall, and secondly, don't preserve the offset engineered into the original setup by GM nearly 65 years ago, in the design stage for the original Corvariants.
I want to leave in here a legacy of guidance, especially with how to preserve that front-rear pressure offset, on Corvairs 1.0 when radials are substituted. And knowing those gross axle ratings would be helpful, even if not necessary.