Quote:
Originally Posted by flybouy
If it's a DOT mandate then I'd think it would have to done by a DOT approved lab.
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Nope. DOT does not test tires in that manner.
When a tire company puts the "DOT" symbol the tire company is
certifying that the tire, when new, is capable of meeting and passing all appropriate standards.
Each company uses it's own QA standards to establish their own performance minimums and test sampling frequency for their tires. In my experience each tire plant is testing tires continuously but since test equipment is expensive as is testing itself they test on a sampling basis.
Sampling is done on a statistical basis by each plant.
Michelin and Goodyear in their RV tire data book show 75 mph max speed for their tires when used in RV application. Goodyear has an exception with their ST type tires where they claim higher speed is allowable. Michelin and Bridgestone do not make ST type tires.
Based on my visual examination of GY Endurance and Marathon tires i believe the Endurance has features which should deliver improved durability. However I do not understand how they managed to make tires that perform at similar speed to LT type tires yet have significantly higher load capacity. It's almost magic.