Quote:
Originally Posted by billrehberg
your tire size is ST225/75R15 scale reading is 3550# on the axle. Add 20% to get a good margin and you get 4.600 or 2,330# for each tire. An ST225/75R15 needs a Minimum of 60 psi to support 2330#.
Now since I advise you add 10# to that inflation so you do not need to mess with inflation when the weather cools down (2% pressure change with each change of 10°F) you would have a target inflation of 66 psi when using your hand gauge.
My trailer weight is 3480; close to your example weight above; when I run through the calculations from you, I get 2088 / tire. So I should still go for 66psi even though slightly lower weight / tire?
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Don't forget we were talking the minimum to support the load, not the inflation get best tire life.
If you review my posts on "Interply Shear", the forces trying to tear the belts off the tire, you would know that I suggest you lower them as much as possible which means that trailers should run the inflation on the tire sidewall.
Yes this might give a rougher "ride" for the trailer. It's up to you to decide how to balance that rough ride against decreasing the chance of suffering a tire failure.
You can Google the term if you want to know more.