Choosing Correct Trailer Tire Load Range and Speed Rating

Updated 08/10/2017 | Published 08/09/2017

Question:

Hi, I was wanting to make sure Im getting the correct load range for my dual axel boat trailer. Fully loaded it will weigh 8500 lbs. Wondering if load range D would work or would load range E be better? Also, how does a dual axel effect the max load? Thanks,

asked by: Marcus

Expert Reply:

Given the same weight load on them, tires of Load Range E will tend to run cooler than tires of Load Range D. The same is true between a LR D tire and a LR C, etc.

Since heat is a trailer tire's worst enemy and the root cause for most failures, using a tire with a higher-rated Load Range is a good idea when you have the option. Tires that are operated right at their maximum load capacity will run hotter than ones that are working at only 75% of their capacity.

Your total trailer weight of 8500-lbs, split over two axles and four wheels/tires, means each tire will see a load of 2125-lbs. This means each LR D tire has a 415-lb safety margin, whereas a LR E tire would have a 705-lb safety margin.

The best ways to keep your tires in good shape are to 1) protect them from UV radiation during storage times by placing inexpensive covers on them; 2) always keeping them fully-inflated to the maximum psi pressure indicated on the tire sidewall; 3) operating them with their rated weight capacity; and 4) operating them within their rated speed. I linked our page for tire storage covers and spare tire covers that will fit this tire size.

The speed rating of most trailer tires is designated as J, or 65-mph. But we do have some select better tires that have an L speed rating, which means good to 75-mph. If you routinely drive long stretches of interstate highway at speeds of 70+ then it is equally important as the correct load range to have tires rated for the speed at which you will operate them.

In the size ST225/75R15, part # LHAW124 that you referenced has an E Load Range (2,830-lb max load at 80-psi) and it carries an L speed rating, good to 75-mph.

expert reply by: Adam R