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Correct Trailer Tire Pressure & What Does Under-Inflation Do to a Tires Weight Capacity


After a recent blowout on a relatively new E rated tire, I would like to move up to F or G rated tires for my 5th wheel trailer with a GVW of 14,000. My concern is the availability of 90 and 110 psi air pressure sources when going to the higher rated tires. I check air pressure on my current tires before each outing and sometimes struggle to reach 80 psi with the sources readily available to me. Would there be any improvement in going to the G or F rated tires if I were only able to run them at 80 psi pressure?


Helpful Expert Reply:

No matter what, special trailer (ST type) tires should ALWAYS be operated in a fully-inflated state. All such tires indicate on their sidewall the maximum psi pressure the tire can hold. You want to keep your tires at this cold tire pressure. (Naturally they will build up more pressure from the heat generated by driving, but at the start of your travel day their cold pressure should always be the maximum pressure noted on the sidewall.)

Special trailer tires are built with stiffer sidewalls to handle vertical loads (rather than with flexible sidewalls that enable better cornering) and unless the tires are fully inflated they cannot deliver their rated weight-carrying performance.

All the tires we sell, such as the Provider ST235/85R16 Radial Trailer Tire # TTWPRG235R16 you referenced, have a weight rating that is dependent on the correct psi pressure. This tire is rated for a maximum load of 4400-lbs at 110-psi pressure. Lower operating pressure would mean the tire will develop more heat and not be able to carry its rated load. Since heat is a tire's worst enemy, observing weight capacity, speed rating and appropriate tire pressure are important to maximizing the life of the tire.

Choose your trailer tires so that you have enough rated weight capacity for the trailer's maximum GVWR along with some safety margin. Running a tire below its maximum capacity means a lower operating temperature and that will tend to lead to longer tire life.

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