Quote:
Originally Posted by wiredgeorge
Interestingly, Trailer King RST ST225/75R-15 LRE and Carlisle Radial Trail HD ST225/75R-15 LRE both have M speed ratings (81 mph). I think 81 mph might be pushing it for my old 96 F250 with drum brakes. I always keep it under 65 mph (I am also not a spring chicken with lightening reflexes). The Trailer King is $75.79 a tire (plus add ons) and the Carlisle is $115.99 (both priced at Walmart for comparison). I think a difference would be the Carlisle factory may have more quality oversight from a US based company where Trailer King? Who knows how much quality control oversight? I am not a tire engineer either and since I know squat about such things, read this stuff on this forum and err on the side of safety and use tires recommended by those that seem to make the most sense.
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The recent requirement imposed on ST tire manufacturers to provide a speed rating for their tires is very beneficial to all users. Speed ratings are directly related to tire fatigue. Not many years ago all ST tires were speed restricted to 65 MPH or less.
At a driving speed of 65 MPH, a tire rated for 65 MPH is providing 100% of its maximum load capacity. As the speed ratings are increased, less and less of that 100% is used.
Many will argue that the ST manufacturers just put speed letters on the tires to satisfy the requirement. If so they committed mail fraud because they had to tell NHTSA the tires were tested.