Trailer tires: tips to choose and use

If you're towing a trailer you need to be aware that your trailer tire needs to be rated to carry the load you expect within the trailer or RV you're hauling. Trailer tires are different from light truck tires or passenger tires and you need to look for the pre-fix of ST (which means Specialty Trailer), instead of an LT or P, in the tire size.

Want to know about trailer tires?

Your tires will need to be balanced and rotated just like your regular vehicle tires. Of course, you need to keep an eye on your tire pressure too.

Tire pressure

If the pressure on your trailer tire is too low, not only will it cause drag, reducing your fuel mileage, but also damage your tire, especially if you need to tow in an area with a lot of backing or with tight corners. While gazing in your rearview, a low-pressure tire will look as if it's going to roll off the rims during a tight corner. If you notice this, check your tire pressure immediately or you and your trailer will run the risk of winding up stranded on the side of the road.

In order to decide what kind of trailer tire you need for your conveyance, you need to weigh your fully loaded RV or trailer. You can usually find a public scale at feed stores and weigh stations; you can also look it up in the yellow pages. Before purchasing tires for your trailer, find out the total weight you're going to be towing.

Once you've determined the total weight of your conveyance, you can choose a trailer tire. You'll be looking for a load rating defined by a letter, which is usually B, C, or D with lighter loads getting the B or C designation.

load range

For example the light truck tire LT235/85R16 D, has a D load range or is equivalent to an 8 ply tire.  The more plies, the stronger the tire. Usually, the higher the letter designation, the greater the ply rating. Higher ply rating equates to a higher load carrying capacity.

Letter  Ply Rating
B  4
C  6
D 8
E 10
F  12
To translate the Load Letter to a ply rating take the letter of the alphabet and multiply by 2. D being the 4th letter will equal an 8 ply, C = 3rd letter x 2 = a 6 ply light truck tire. Note that a tire may not actually have 8 plies, but will be the equivalent strength of 8 of the plies which were used when tires were made using cotton cords.

You will also find tire pressure has a direct relationship with the load you carry. The tire mentioned above is designated a Light Truck tire (LT),size of 235/85, of radial construction (R) , the next number is the wheel diameter the tire will fit, and the D is the load range.

Many load carrying tires have a maximum load capacity stamped on the sidewall, or the tire dealer may have technical specifications for that particular tire, if you ask them.

Just remember, just because you have a high load capacity trailer tire, you still need to check on your axle weights and suspension components to determine how much weight your trailer can actually carry.

If your trailer has a single axle, you must divide the total weight between the two trailer tires, a double axle trailer, divides the total weight by four, and so on for triple axles or more. You'll also need to check you haven't exceeded your gross vehicle weight rating (GVWR). Weigh stations where heavy trailers must stop will fine you for exceeding your GVWR. (Recreation Vehicles are exempt in most US states from routine weight control inspection.


In summary, to choose a trailer tire, take into consideration:

  • the gross vehicle weight,
  • the weight each individual tire will carry,
  • the speed you intend to travel and,
  • any characteristics of your intended use that might be special.

Once you have bought and installed your trailer tires:

  • Check the pressure regularly, especially between periods of non-use.
  • Inspect the operating diameter of the tire and adjust pressure accordingly. This is especially important when adding or removing any weight from your trailer's load.
  • Regularly balance and rotate the tires

 These steps can help save you from being stranded on the side of the road and ensure a long and satisfactory experience with your trailer tires.

Also read Trailer tires wheels for additional information.


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