What Could Cause Boat Trailer Tires to Wear More on Inside Tread of Both Left and Right Tires
Updated 09/27/2025 | Published 06/15/2015
Question:
tires wearing on the inside tread of both left and right side
asked by: Jose
Expert Reply:
The most common cause for trailer tires' tread to wear more on their inside edge than their outside edge is overloading of the trailer. If a trailer axle is overloaded it's center will bend down toward the road surface and this will change its geometry, causing the inside edges of the tires to make more contact with the road surface than the outside edges. This will lead to uneven tread wear with more wear on the insides.
Please see the linked diagram.
An axle in good condition that is not overloaded will keep the tires' surfaces evenly placed on the road and this will result in even tread wear as long as the tires are properly inflated. Only special trailer type tires (ST type) should be used on a trailer and they should always be inflated to the maximum psi pressure rating shown on the tire sidewall.
An under-inflated tire will tend to wear at both outside edges while an over-inflated tire will tend to wear more at the center of the tread.
Product Page this Question was Asked From
Loadstar ST205/75D15 Bias Trailer Tire - Load Range C
- Trailer Tires and Wheels
- Tire Only
- Bias Ply Tire
- Load Range C
- 205/75-15
- 15 Inch
- Kenda
more information >
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Bruce
9/27/2025
I have the problem of inside tire wear on a utility trailer. It came with 480-12 4-On-4 tires/wheels. Trailer has a 1,000 lb weight limit. I always ran the tires at their marked psi, but got fast uneven wear and blowouts. A few years ago I replaced the axle with the CE33201GA CE Smith Trailer Axle Beam 57-1/2" Long - 1.8K from etrailer because of spindle damage. I continued to use the 12" tires but got tired of frequent replacements, so a year ago I put ST175/80D13 175/80 D 13 tires/wheels on the Smith axle inflated to 50 psi as marked on tire. I was carrying a load of about 700 pounds. I put about 2,000 miles on this summer on a new set of tires I bought from Discount Tire and there was excessive wear on the inside of both tires. Researched your Q&A and found suggestions about camber. I used a straight edge on the top of the axle and the center was about 1/16" lower than the ends of the axle, which is in the correct direction. So then I checked wheel/tire alignment with the trailer frame and found that there was a toe-out of 1/4" or more on both tires. This would indicate to me that since both were the same, the axle was square with the trailer frame, but the spindles were out of line with the axle in a horizontal direction. I removed the axle, flipped it end-for-end and sure enough I now have toe-in of about the same amount. I have read that toe-out can cause inside wear. Now I'm concerned that on my next trip with toe-in I will get excessive wear on the outside edges. Is there any fix for this problem other than a better axle? If I then have wear on both edges, higher inflation would move wear to the center, but that would exceed the psi marked on the tire so I am hesitant to do that.