I havn't ever had a problem with load range D tires at all. My MTZ were only 2600lbs load rating and I pulled 10K+ trailers all the time without a single issue. I just bought some Cooper STT Load range D and there 3195lbs. I have run Ds on my cummins and my powerstrokes and have never had a failure. Everyone on here says you can't run Ds on these trucks and I don't by it. As long as the tires will handle the load don't be worried about D or E.