Can You Put Car Tires On A Trailer? (And Vice-Versa)

Generally speaking, car and trailer tires are sold separately, marketed as their own thing, rather than simply sold as "tires," which suggests they might not be interchangeable. Is this the case, or can car tires be put on a trailer, and trailer tires put on a car?

The answer is unlikely to be straightforward, as the world of tires can actually be quite complex. For example, do you know what the colorful stripes on tires are used for, or what the yellow dots on tires mean? With that being said, we've done the research to find out exactly what the rules and regulations surrounding trailer tires are, and, as it happens, it's actually pretty black-and-white — the answer is no.

According to NTB Tire And Service Centers, it's very clear that you should not be using car tires on a trailer, and for a few very good reasons. Chiefly, trailer tires — also known as ST tires — are built to different standards than typical car tires, which makes them unsafe for use on a vehicle.

Trailers are generally used for carrying heavy or bulky items that will not fit in a car, such as motorbikes, other cars, or boats. As a result, trailer tires are manufactured with a higher load capacity, in addition to stiffer sidewalls, and they can withstand higher operating pressures. Car tires are not designed to withstand such stresses, and so have no need to boast stiff sidewalls and higher load capacities, which is what makes them totally unsuitable for use on trailers.

Trailer tires typically sport a 40% higher load capacity than most car tires, which is how they manage to haul big loads much safer than car tires. They are also rated to withstand much higher internal pressures, with most ST tires taking 65 psi (pound-force per square inch), whereas a typical car tire requires only between 31 and 35 psi. The higher pressure of a trailer tire helps to distribute the trailer's weight more evenly, and car tires are simply not developed to serve this purpose, with weaker sidewalls, that will likely pop when under the same pressures and strains of a trailer tire.

Much in the same way, trailer tires are also quite dangerous to use on cars, and it once again all comes down to the basic design and structure of each type of tire. Another characteristic of trailer tires is a lower maximum speed rating. Generally, trailer tires are rated to 65 mph — or occasionally 75 mph if rated to allow an additional 10 psi of pressure — whereas car tires are generally rated for much higher speeds.

Succinctly, these two tire types are too different to be interchange, and trailer tires would not be able to take the heat, speed, nor pressure of a car. Fortunately, understanding and knowing a few key tips about buying new car tires means it's easy to pick the correct tire for each application, so there should be no reason why anyone would accidentally equip their car with trailer tires, or indeed vice versa.