While it is possible to buy Special Trailer (ST) tires with a tire speed rating of 80+ MPH, some ST tires put on travel trailers and RV fifth wheels by manufacturers have a maximum tire speed rating of just 65 MPH.
Maximum Speed Rating, Maximum Tire Pressure, and Maximum Load Rating
You can drive faster than the maximum speed rating but in order to do that, you need to increase your cold inflation pressure by about 10 psi (without exceeding the maximum PSI stamped on the tire) for every 10 mph over 65 that you are driving, as well as devalue your load carrying capacity by 10%. In practice, this isn’t usually possible since manufacturers often supply tires that will handle the RV’s GVWR when inflated to maximum tire pressure.
If you’re maxing out the load rating of your trailer’s tires it is imperative that you keep your speed at or below the maximum rating. Driving faster will, at the least, shorten the life of the tires and may result in catastrophic failure on the road.
When buying replacement tires you may want to consider upgrading to a higher load range tire, just fas s safety margin, and you may be able to lower the tire pressure a little for a softer ride. Don’t forget to buy tires with a speed rating that suits your driving needs.
You may also be interested in these articles:
RV Tire Maintenance Tips
How to Choose the Right Tires For Your Towable RV