I'm starting to researching tires and finding (like most things on the pop up) the more you dig into something the more there is to learn... Anyways, having trouble figuring out what all the codes mean on the tires. The tires I have are ST 145R12 I understand the size and radial part. However, after that is E 95L. Is this part of the speed rating? Trying to figure out the speed and load rating. Thanks!