Suspension help

Cummins12V98 wrote:
Wes, that's impressive!

I just know I had an onboard in cab pressure gage that I could air up and down each bag. At 5psi unloaded when the RV was added the pressure went to 30psi.

No math formula need for me just visual proof.

That is why I always ask people if the air pressure they are referring to is loaded of unloaded. Still I don't understand why tires are not affected in the same way.

Thanks. If, and only if, my reasoning is correct, then your airbags are probably sized less than the bags I described. With less square inches of bag, the pressure would rise dramatically more than my examples.

For the same proportional size reason, tires most likely do rise in pressure when additional load is applied to the vehicle. But there is a lot more square inches of area in a tire to spread the increase around. Each square inch would therefore bear only a small increase, probably not even noticeable if one did pay strict attention to minor differences in the tire guage. One other factor is that a truck guage often squeezes a lot of graduations on the same short ruler in order to measure over 100 pounds when necessary. This means that slight variations in loaded vs non-loaded measurements would not read so obvious.

I suppose one could calculate the actual surface area of a tire. Including some inner steel wheel surface, the tire is merely a cylinder again, but without the end discs. For example, a 3 foot tall tire (diameter) would exceed 9 feet tall were the tire "cut" and the donut-shaped tube "straightened out". In my opinion, that is a big cylinder and it is no wonder that relatively minor pressure increases from added load are not obvious.

Wes
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