Introduction
Have you noticed that the tires on your trailer are wearing funny? This may be especially noticeable on car trailers (flatbeds) and boar trailers.
Below is (2) charts and some photos to help you diagnose the problem:
Charts
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Under Inflation – Wear on both edges:
Under inflation of a tire reduces its tread life by increasing the tread wear on its outside edges, or shoulders. It also generates excessive heat which reduces tire toughness. Finally, it reduces fuel economy through increased rolling resistance because soft tires make your trailer and vehicle work harder. Abnormal tire wear may also be caused by misalignment. |
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Over Inflation – Wear in center:
When a tire is over inflated, the center of the tread bears most of the load and wears out faster than the outside edges. Uneven wear reduces the useful life of a tire. |
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Cupping – Cups or dips in the tread:
Cupping (also called dipping) is most common on front tires, although rear tires can cup as well. It may be a sign that wheels are out of balance, bearings are loose or that suspension parts are worn out. |
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Inside or Outside Wear:
If the edges of your tire tread take on a sawtooth or feathered appearance, it’s because of erratic scrubbing against the road. The solution is an alignment correction. If the inside of tire is smooth or shows signs of excessive wearing it is likely the result of overloading the trailer. |
Some wear issues could be from improper tire inflation. Make sure you’re running the proper tire pressure in your trailer tires.
| Tire Size | Max P.S.I Cold |
| 4.80×12 | 90 psi |
| 175/85D13 | 50 psi |
| 205/75D14 | 50 psi |
| 205/75D15 | 50 psi |
| 225/75D15 | 65 psi |
| 235/80R16 | 90 psi |
| 235/85R16 | 90 psi |
Photo Examples:
(Wear from being overloaded)
(Wear from being over inflated)
(Wear from being under inflated)
(Wear from wheel locking up or skidding)
(Cupping – see the high and low sections along the left)
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About The Author
Jim Oaks is the founder of The Ranger Station, one of the longest-running Ford Ranger enthusiast communities on the web. He has spent over three decades owning, modifying, repairing, and driving Ford Rangers on the street, trail, and cross-country routes.
Since launching TheRangerStation.com in 1999, Jim has documented thousands of real-world Ranger builds, technical repairs, drivetrain swaps, suspension modifications, and off-road tests contributed by owners worldwide. His work has been referenced by enthusiasts, mechanics, and off-road builders looking for practical, experience-based information rather than theoretical advice.
Jim’s hands-on experience includes long-distance overland travel, trail use, drivetrain and axle upgrades, suspension tuning, and platform comparisons across multiple Ranger generations. The content published on The Ranger Station is grounded in first-hand experience and community-verified data, not marketing claims or generic specifications.