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Here is some surprising info found on the Model T Forum I thought was interesting. The question was why his Model T valve stems were failing. The answer is:
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ANSWER: Usually a valve stem failure is caused by one of two things - the tire slipping on the rim, carrying the tube with it, or the tube it self "sloshing" in the tire. Both of these are usually caused by insufficient pressure - clinchers take 20 p.s.i. per inch of width, so on 30 x 3 1/2 tires you need 70 PSI. (3.5 X 20 = 70 PSI) If you go with a standard oversize, which is 31 x 4, that puts it up to 80 PSI. (4 X 20 = 80 PSI)
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Dont underinflate clinchers.... a lot of people seem to think 40-50 PSI is OK and wonder why they have tire problems. Clinchers are high pressure tires and designed to run in that way.
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There may be another, tho... If your rims have been powder coated, the slickness of the finish *can* cause the tire to move even at 70 PSI. You may need to "de-coat" insides to get rid of that glass smooth finish in the rim where the tire sits.
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One reservation I have is if your tires have a lot of age on them the sidewalls won't hold to this theory.
Here is some surprising info found on the Model T Forum I thought was interesting. The question was why his Model T valve stems were failing. The answer is:
*
ANSWER: Usually a valve stem failure is caused by one of two things - the tire slipping on the rim, carrying the tube with it, or the tube it self "sloshing" in the tire. Both of these are usually caused by insufficient pressure - clinchers take 20 p.s.i. per inch of width, so on 30 x 3 1/2 tires you need 70 PSI. (3.5 X 20 = 70 PSI) If you go with a standard oversize, which is 31 x 4, that puts it up to 80 PSI. (4 X 20 = 80 PSI)
*
Dont underinflate clinchers.... a lot of people seem to think 40-50 PSI is OK and wonder why they have tire problems. Clinchers are high pressure tires and designed to run in that way.
*
There may be another, tho... If your rims have been powder coated, the slickness of the finish *can* cause the tire to move even at 70 PSI. You may need to "de-coat" insides to get rid of that glass smooth finish in the rim where the tire sits.
*
One reservation I have is if your tires have a lot of age on them the sidewalls won't hold to this theory.