Best ST225/75R15 Trailer Tires for Higher Speed Driving

Question:

My travel trailer tires are ST 225/75R15, Load Range D, Load Index 113/8 L, 75mph Max Speed rating. Max Pressure cold 65 PSI. These are original equipment on a 2017 Duthcman Aspen Trail. Is it really safe to tow at 75 mph? I have had several people tell me that it is never safe to tow above 65 mph. I have had the trailer weighed at 6940 lbs on the trailer axels while hitch to my pickup.

asked by: Peter D

Expert Reply:

The load and speed ratings of the ST225/75R15 trailer tires your 2017 Dutchman Aspen travel trailer are maximum capacities for the tires themselves. The 75-mph maximum speed of an L-rated tire does not indicate a recommendation to tow a trailer at that speed.

Safe towing speeds naturally vary based on the nature of the road (dead-straight flat interstate versus winding two-lane back roads), the weather conditions and the total weight of the truck and trailer as a combined system. Also, the value of your own experience towing that trailer cannot be over-rated.

In a towing setup with a 7K trailer and a truck that also weighs about that much I would certainly be cautious about towing at 75-mph. Doing so means your tires will be operating at their limit, meaning you no longer have a safety margin. Higher speed means more heat, and since heat is the fundamental cause for most tire failure I would recommend you not tow at 75-mph for extended periods. Brief periods of higher speed, such as when passing other vehicles, is one thing but continuous driving at the limit for your tires is not recommended.

If you do want to be able to drive at 70-mph for long periods you would do well to replace your tires with M-rated ones (good to 81-mph) when the time comes for new tires. It is always a good safety practice to avoid any components in your towing system being operated at their limits.

In your tire size ST225/75R15 we offer the Kenda radial # AM10303 which has an 81-mph speed rating as well as a Load Range E weight rating. By using a tire with both more speed and weight capacity you add safety margin to your towing system and with these tires installed on your trailer I would not worry about steady 75-mph driving when road and weather conditions allow it.

expert reply by: Adam R