Originally Posted by Witch Doctor
Maxxis Corporation just got back to me they said that they can only tell me that they are safe at any rated highway speed by law. They also said they do not rate the ST tire for speed rating. I asked about the Amazon speed rating of 106 MPH she said I do not know where Amazon is getting there tires, but Maxxis will say they are safe at any posted speed limit in the USA. They will not commit to any recommended speed limit. She said if the speed limit is 65 they are good if it is 75 they are still good. They just will not commit. She also said it's not required by law to produce a max speed for there tire. Still confused maybe Tireman9 can make sense of it. I thought that every DOT tire had to have max limit that you can travel at a constant speed. I guess not according to Maxxis Corporate office in Georgia.
Bet they won't give you that in writing. According to US Tire & Rim Association ST type tires are rated for a max of 65 mph. The exception would be for GY and TowMax who have issued Tech Builtin to Tire Rack on the increase in max speed up to 75 but not above but only with an increase of 10 psi cold and NO increase in load.
Some new ST type tires are now being made with a higher than 65 speed rating but the tires would have a speed symbol molded on the tire sidewall. No symbol = 65 MAX per TRA. TRA is the reference used by DOT. Some ST tires have a L rating which is 75.
RE Customer Service person. You don't think they are experienced tire engineers do you? I bet they are relatively new hires with a book of standard answers for standard questions.
I got into a discussion with Michelin person just last week on incorrect Load Range information published on their web site and used in the ref book she was using. She was trying to tell me their passenger tire had a "C" Load Range.
No such rating in TRA or ETRTO which is European standard book or JATMA which is book for Asia. After asking a few questions and pointing out the contradictions she admitted that her info appeared to be incorrect and would discuss with her supervisor.
I write a blog on RV tire application and safety. RVTireSafety.com
Also give seminars on tires at RV events across the US. 40 years experience as tire design & quality engineer for major tire mfg. Freelander 23QB on Chevy chassis is my RV