Troubleshooting Outer Edge of Trailer Tires that Wear

Question:

I have an enclosed snowmobile trailer, total combined weight of trailer and sleds are 2100 lb. Current tires are st145/ 8012, load range E, speed rating m, Max 80 psi. Tire pressure is 80 psi, always running trailer at 74 mph. Outer treads are significantly wearing more than middle tread. Outer treads are at 3/32 to 4/32, middle treads at 5/32 to 6/32. What would cause the outer Treads to wear more than middle tread even though psi is at 80 psi? Tires have aprx 10k miles on them. Will be replacing in the fall.

asked by: John G

Expert Reply:

Typically when tires wear out on the outer edges it's a pressure issue (too much) for how much weight is on the trailer, the speed rating could be a problem too but it sounds like you are good there. It could also be an alignment issue but if it's same problem on both tires that wouldn't be as likely.

What I would do is when it's time to replace the tires go with a lower Load Range so that you can use a lower pressure like the # AM10130 which has a psi rating of 65.

expert reply by: Jameson C

John G.

2/29/2024

Correct me if wrong...I assumed outer wear would indicate under inflation? Can I still run 74mph with a load range D tire rated at 65mph then? Or run a load range E with less tire pressure...say 75psi?

Jameson C.

2/29/2024

@JohnG On a trailer outer edge wear on both tires most likely indicates that the axle is rated too high for the weight of the trailer if anything as the axles have a bow built into them that is flattened out once weight is put on it. Or there happens to be an alignment problem on the trailer. If it's an inflation problem the more I think of it it would make sense it's under inflation. Are you lowering the tire pressure once they get hot possibly? If so, what you are supposed to do is inflate the tires to max PSI when cold and then not change anything as the PSI increases due to temperature.

John G.

2/29/2024