Trailer tire basics
Trailers should run on ST (special trailer) tires. Their stiffer sidewalls are designed to reduce trailer sway, which passenger and light truck tires, with more flexible sidewalls, can make worse.[1 · Oct 29, 2026]
The ground rules
- Don't put P or LT tires on a trailer, and don't put ST tires on a car or truck.[1 · Oct 29, 2026]
- ST tires carry roughly 10% more load than a similar LT tire and nearly 40% more than a similar passenger tire.[1 · Oct 29, 2026]
- All the tires on the trailer should be identical in size.[1 · Oct 29, 2026]
- Their combined capacity must at least equal the trailer's gross weight rating, and Carlisle recommends it exceed the loaded weight by 20%.[1 · Oct 29, 2026]
- If one tire fails on a tandem axle, replace both tires on that side.[1 · Oct 29, 2026]
Speed
Carlisle says most ST trailer tires have a maximum speed rating of 65 mph, and recommends staying at or below 60 mph while towing.[1 · Oct 29, 2026] Check the sidewall and the tire maker's specs for your exact tire.
Load range and pressure
| ST load range | Max load pressure |
|---|---|
| B | 35 psi |
| C | 50 psi |
| D | 65 psi |
| E | 80 psi |
Pressures from Tire Rack's load range table.[2 · Oct 29, 2026] Underinflation is hard on trailer tires: Carlisle says running 30% underinflated can cut tire life by about 55%. Check inflation with a good tire gauge.[1 · Oct 29, 2026]
When to replace
Carlisle puts the average trailer tire life at 3 to 5 years and says to replace them after five years in all cases, even if the tread looks fine.[1 · Oct 29, 2026] The tire's age is in the last four digits of the DOT code: see tire date codes.[3 · Oct 29, 2026]
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Sources: 1. Carlisle Transportation Products, Trailer tires: tips and best practices (PDF). 2. Tire Rack, What are load ranges and ply ratings?. 3. Tire Industry Association, Reading a tire sidewall. Checked Oct 29, 2026. Size dimensions, revolutions per mile and speedometer figures are our own arithmetic from the size code. Trademarks belong to their owners; figures are restated in our own words and tables, not reproduced.