What is the Difference Between a ST205/75/D15 and ST205/75/R15 Trailer Tire

Updated 11/01/2020 | Published 10/31/2020

Products Featured in This Question

Kenda Karrier ST205/75R15 Trailer Tire with Black Mod Wheel - 5 on 4-1/2

(2643)

$179.52

Karrier ST205/75R15 Radial Trailer Tire - Load Range C

(2084)

$122.69

Question:

My boat trailer tires are ST205/75D15 and the Kenda Karrier tires you sell are ST205/75R15. Are these tires different in size or same, or similar and how? Thank you in advance for help

asked by: Alan D

Helpful Expert Reply:

The ST205/75D15 tire that you've currently got are the same size as a tire like the Karrier ST205/75R15 Radial Trailer Tire - Load Range C # AM10244, but the difference is that your D15 tire is a bias-ply tire where the Kenda Karrier R15 tires are radial tires. The cords inside a bias ply tire run at a 32 degree angle to the direction of travel, whereas cords on a radial tire run at a 90 degree angle, or across the tire from wheel lip to wheel lip.

This really just means that radial tires are going to flex more, which provides better ground contact, traction, stability, and tread wear. A radial tire will normally run cooler than a bias ply tire, and since cooler tires last longer, radials generally outlast bias ply tires.

The Karrier # AM10244 tires are a load range C tire with a capacity of 1820-lbs per tire, so a set of tires would be ideal for trailers with 2140-lbs or less capacity. There is also a load range D tire available in this size with part # AM10245 and a capacity of 2150-lbs per tire (4300-lbs total with single axle).

I've linked our entire selection of tires that are ST205/75/R15 for you to check out, as well as a helpful article we did on trailer tires that explains more about the differences between various tires.

expert reply by: Erik B