Recommendation to Replace ST225/75D-15 Tires on MacGregor Boat Trailer

Question:

What do you recommend for a MacGregor 26M Boat Trailer Tire and or wheel assembly: Load Plate: GVWR - 4200 lbs GAWR - 4200 lbs With ST225/75D-15 D Tires It is a single axle. Current tires being replaced due to age: CARLISLE SPORT TRAIL ST225/75D15 Hub pattern is 5 on 4.5 The current tires are bias - I dont yet have much towing experience with it to know if sway will be a major consideration. Do modern ST radials have stiff enough sidewalls compared to bias to make that a non-issue?

asked by: Jim

Helpful Expert Reply:

Replacing the existing bias ply ST225/75D-15 tires on your boat trailer with radial ply alternatives is a great idea, as the radial construction is going to allow for better traction and cooler operation at higher speeds on the highway. Ideally it will result in a bit of a smoother ride when compared to the bias units the trailer's equipped with (along with a longer lifespan), however it's not going to really affect sway.

Technically speaking bias ply tires actually have a stiffer sidewall than radial tires, and this is what makes bias units a better option if you primarily planned on using the trailer for off-road applications (such as farm use, etc). The stiffer sidewall though can also lead to a rougher ride, and higher temperatures, when traveling at higher speeds on the highway.

For your boat trailer I specifically recommend the Provider ST225/75R15 Radial Trailer Tire # TTWTRTM2257515D. This is an excellent tire that features a maximum load of 2,540 pounds at 65 psi and a speed rating of 81 mph (most likely the speed rating on the tires you're replacing were 65 mph).

You could pair this with the wheel, a 15" Galvanized Wheel with part # AM20524. These do not come pre-mounted but you could easily get them mounted at a local shop upon arrival.

I have attached a few short video reviews below that you can check out as well.

expert reply by: Chris R