Higher Capacity ST175/80-13 Trailer Tires for a Boat Trailer that Keeps Blowing Tires

Question:

Over the past 7-8 years I have had several trailer tires blow out or come apart while trailering my 21 ft. center console boat. My trailer is double axle with ST 175/80R13 C rated tires. Calculated weight of boat, motor, trailer, trolling motor, batteries, full tank gas, fishing gear etc is around 4900-5000 lbs. also included a 20 buffer. Assuming my trailer is tongue level , which I think it is, each tire is holding up around 1250 lbs. I regularly check to make sure the tire pressure is at 50 psi. Question 1. Do you think that I am using the right size tire for the weight of my rig? Should I consider using a ST 185/80r13 tire? Question 2 . Can I put two 185s on the back axle and use two 175foot on the front axle or do I need to replace all four at one time? Please give me your thoughts or suggestions. Thank you very much.

asked by: Robert G

Expert Reply:

Actually, 13 inch tires are becoming less common. So you may want to think about going to a 14 inch in the future. But for now you can get 13 inch tires. Going up to a 185 from a 175 should not be necessary unless you are overloading the tires you have. That is possible given the weight of the trailer.

I recommend stepping up to a load range D tire in size ST175/80-13 such as # AM1ST77 for a bias ply, or # AM10210 for a radial. These tires are rated for 1,610 pounds at 65 psi. So 4 of them have a 6,440 pound capacity all together. That is nearly 1000 pounds more than the tires you currently have. Please note that the higher capacity tires will not increase the capacity of the trailer.

Also, always make sure the trailer tires are inflated to the maximum psi on the the tire. You would not want to mix tire sizes as that could lead to tracking problems and uneven tire wear.

expert reply by: Michael H