Originally Posted by lbrjet
A blanket statement saying all ST must be run at max pressure is just silly. You are going to build heat if your load exceeds the pressure rating for that load regardless of whether the tire is a C D or E. Running 65 in an E on a D load is not going to hurt anything, but it will give you a stronger tire.
Under inflating a ST tire will generate a lot of heat. When traveling I always check my tires cold and have maximum PSI (as rated on the tire) in the tires. Then when we stop I check the tires for over heating. Never yet had tires running hot on me. And that includes traveling through Texas- Arizona- Utah- Montana- Wyoming etc...
And it's not advisable to jump two ratings on tires with the same rims. Going up one lever is what the manufacturers allow ( ei, C to a D, D to a E etc..) but not a C to an E rating.
ST = Special Trailer tires are designed to take the lateral stresses placed on trailer tires, Truck tires aren't). If you want to see an exaggeration then when backing tightly into a camping spot get out and take a look at how the tires are angled. Looks like they will pop off the rims they are twisted so badly.
If you would like to understand ST verses LT tires then watch this video: