Operation Instructions for ST Tire Speed Ratings

Updated 02/09/2016 | Published 02/08/2016

Question:

I have read several places that any ST tire no matter what size, no matter what ply, just by the fact that it is an ST tire it has a speed rating of 65 mph. Why is it that all over your web site you are saying these ST tires have a speed rating of 81 mph. 81 mph with a 65 mph rated tire is unsafe and leads to more heat and thus more blowouts which is what most RV owners have a problem with.

asked by: Bob C

Helpful Expert Reply:

I can help you understand the reason there is different information on our website.

Special trailer tires have a maximum speed rating, just like passenger car and truck tires. Older tires have no special marking to designate a limit. Their maximum speed is 65 mph. Newer tires, those manufactured in 2015 and later, should have one of the following codes on the sidewall to show their rating:

M - 81 mph
L - 75 mph
J - 62 mph

If a trailer tire has any other marking to designate maximum speed rating, follow it. You will also want to match your ST Tires. You should always use tires of the same size, load range, and construction on a trailer. If you use tires that don't match, you could experience problems of overloading and overheating, which can lead to tire failure.

I have linked a Help Article on trailer tires for your convenience.

expert reply by: Jackie C