Trailer Tire Ply RatingsUnlike your car, your trailer is designed to handle heavy loads. In order to properly and safely tow this weight, you need tires with the right ply rating.
What is a Ply?
Ply is a standard rating that refers to the load capacity of your tire in terms of how its sidewall is constructed. Originally, this rating referred to the actual number of cotton layers used to reinforce each tire. As manufacturers began using steel plies and radial tires, the rating converted from a number to a letter that represents the same amount of strength. This letter rating is referred to as the load range and is indicated on the side of every tire.
Why Is Ply Important?
Towing a trailer with weak tires is unsafe. When the sidewall of a tire is unable to handle a given weight, the tire compresses into the road. This weakens its structure and speeds up the wearing process. Not only that, but it’s likely to cause a dangerous blowout, especially when rotating at high speeds.
Choosing a Ply
In order to choose your ply rating, you need to evaluate what you intend to carry. Trailers are built to carry heavy loads, so you obviously need something stronger than what you use on your sedan. Start with your trailer’s gross vehicle weight rating found behind your hitch. Divide that number by the number of tires you’re running to get the capacity of each separate tire. It’s a good idea to go with a maximum load rating of 20 percent more than your gross vehicle weight rating. This gives you a safety buffer to account for differences in temperature. If you own a fifth wheel or other irregular configuration, you will need to use your gross axle weight rating in order to account for the unequal weight distribution.
Ask a Pro
When in doubt, ask a trailer tire professional. Consult your manufacturer or seek help from a tire supplier to ensure that you are towing safely and efficiently.