No. Passenger-car (P-metric) tires do not belong on a trailer. Trailers need Special Trailer (ST) tires, which use stiffer, thicker sidewalls, higher inflation pressures, and heavier internal construction to carry loads without swaying. Industry practice also derates a P tire's load capacity by roughly ten percent on a trailer, so it carries less than its sidewall suggests.
A trailer needs the opposite of what a car tire does
A trailer has no steering axle and no drive axle. Its tires never have to grip the pavement to corner or put down power. What they must do instead is carry a heavy load in a straight line for hours and resist the side-to-side flex that turns into sway at highway speed.
Car tires are engineered the other way around. Their sidewalls are deliberately flexible so the tread stays flat on the road for grip and the ride stays comfortable. That flexibility is a feature under a car and a liability under a trailer: every bit of sidewall squirm behind your hitch feeds the pendulum motion that drivers feel as sway.
ST vs P-metric: the design differences
ST tires are built around load and stability rather than traction. The sidewalls are thicker and stiffer, the internal cords are heavier, and the rated cold inflation pressures are much higher than anything a passenger tire runs. Higher pressure keeps the casing from flexing under load, and less flex means less heat.
| Attribute | ST (Special Trailer) | P-metric (passenger) |
|---|---|---|
| Sidewall | Thick and stiff, built to resist lateral flex and sway | Flexible, tuned for ride comfort and cornering grip |
| Typical cold pressure | High — commonly 50 psi (Load Range C) to 65 psi (D) or 80 psi (E) | Commonly around 32 to 36 psi |
| Load logic | Carries its full rated load at sidewall pressure, sized for sustained max weight | Rated for a car; derated roughly 10% when used on a trailer |
| Designed for | Straight-line towing with no steering or drive forces | Steering response, braking, and drive traction |
| Use on a trailer | Yes — the standard choice | Not recommended |
What goes wrong with P tires on a trailer
Three things, and they compound. First, sway: the soft sidewalls let the trailer oscillate behind the tow vehicle, and once sway starts it can build instead of damping out. Second, heat: a loaded trailer works a passenger sidewall far harder than a car ever would, and repeated flexing builds heat in the casing — the classic path to a highway blowout, especially in hot weather at full load.
Third, capacity: because a P tire was rated for passenger-car duty, the industry convention is to knock roughly ten percent off its load rating when it is mounted on a trailer. A setup that looked fine on paper can quietly end up overloaded. If your trailer is due for rubber, start with purpose-built trailer tires in the correct load range.
Where LT tires fit
Light Truck (LT) tires are the one partial exception. They are built with reinforced casings for hauling, and some heavy trailers — large fifth-wheels and equipment trailers among them — come fitted with LT tires from the factory. If you go that route, the LT tire must meet or exceed the axle's load requirement at its rated pressure. For the vast majority of utility, boat, cargo, and camper trailers, though, ST remains the standard and the simplest correct answer.
If you are replacing wheels at the same time, browse the trailer wheels collection and confirm your fitment with our bolt pattern measuring guide before ordering.
FAQ
Can I put ST tires on my car or truck instead?
No. ST tires are not designed for the steering grip, braking traction, or drive forces a powered vehicle demands. They belong on trailer axles only, and running them on a car or truck is unsafe.
How do I know if a tire is a trailer tire?
Read the size on the sidewall. Trailer tires carry the prefix ST — for example, ST205/75R15 — where a passenger tire reads P205/75R15 or simply 205/75R15.
Do trailer tires have a speed rating I need to follow?
Yes. Many older ST tires default to a 65 mph limit, while modern ST radials carry a letter rating on the sidewall — commonly L (75 mph), M (81 mph), or N (87 mph). Check your tire and do not tow faster than it is rated.
What pressure should ST tires run at?
Trailer tire makers generally recommend inflating ST tires to the maximum cold pressure printed on the sidewall. Underinflation causes flex and heat, which is the main killer of trailer tires.
When you are ready to swap, Cheap2Go Tires ships trailer tires and wheels with free shipping from our Florida warehouse.