Originally posted by XSrcing
also,the tire must be able to maintain its rated speed for at least 2 hours before failure.
Hmmm. According to SAE 1561 and the ECE European spec (don't know that spec number offhand), the tire only needs to pass through that speed step to pass that requirement. We test several steps beyond that for safety purposes, but the specs say nothing about 2 hours.
Ferd