How to Fill Tires on Trailer that Have Different PSI Maximums

Question:

I have two different trailer tires same size of course but with two different pressure ratings? Do i fill all 4 to the same 50 psi or the two that are rated to 65 psi to 65 psi and the two to 50 psi to 50 psi?

asked by: Matt K

Expert Reply:

Trailer tires should always be inflated to the maximum psi that is listed on their sidewalls. Because their load capacity is based on the them being filled to their maximum psi, under-inflating a tire will essentially reduce its capacity to an unknown rating. For the time being, I recommend filling each tire on your trailer to its specific maximum psi as listed.

With that being said, it sounds like you have tires of the same size but of different load ratings on your trailer. I highly recommend switching out some of your tires so that they all feature the same load capacity. Using tires with different load ranges on the trailer will likely lead to uneven tire wear, possible tracking/ride quality issues, and one tire may build up excessive heat (which is the most common cause of trailer tire failure).

Based on the psi ratings you listed, you likely have a couple ST225/75R15 Load Range D tires, which have a 2,540 pound capacity at 65 psi, and a couple Load Range C tires, which feature a 2,150 pound capacity at 50 psi. I recommend swapping out the two Load Range C tires with a Load Range D like the Karrier # AM10256 so that they all match on the trailer.

I have attached a short video demonstration on this particular tire, as well as a link that will take you to our available selection of ST225/75-15 tires with a Load Range D that you can look through.

expert reply by: Chris R