Difference Between 75R14 and 75D14 Tires for Boat Trailer

Question:

i have a boat trailer the tires are ST 75 R 14, can I use 75 D 14 tires on this trailer?

asked by: David C

Expert Reply:

Yes, the 75R14 and 75D14 are going to have the same aspect ratio but will be constructed differently. You can use them, but the # AM1ST86 are likely not going to be the ideal solution for your trailer. When reading this tire spec, your current tire is a Radial tire (R) where the # AM1ST86 is a bias ply tire (D). Radial tires are typically better at flexing and providing more contact with the road, where bias ply tires provide less sidewall flexing, so they're normally not ideal for highway travel.

When taking this into consideration, a better solution is going to be the Castle Rock ST205/75R14 Radial Trailer Tire - Load Range C # LHCK201. These are a radial tire, so they'll be great for highway travel and dissipating heat that can cause tire malfunction. These tires are a Load Range C tire with a 1760-lbs per tire capacity (3520-lbs total for single axle trailer), so as long as your boat and trailer weigh less than that, these would be a good choice. If you've got a heavier boat/trailer, please let me know what the GVWR is and I can work to find you an appropriate replacement.

I've also linked some of our helpful articles on trailer tires that you may want to have a look at, as well.

expert reply by: Erik B