We have had both LR D and LR E ST tires in the size above and didn't notice any difference in reliability or longevity. We have had similar success with either load rating getting 4 years of use before replacing them. My take is brand and tire care are more pertinent in terms of an ST tire's ability to deliver reliable service, we find that 4 years is the cut-off for us and always replace all four tires without question. Thankfully we have never had any blowouts while underway and we do tend to go beyond 65mph from time to time.