Wheel and Tire Combo Recommendation to Replace a 78-14 Tire

Updated 03/04/2015 | Published 03/03/2015

Question:

I have a boat trailer with old tires marked 78-14. Looks like maximum load = 1865 lbs. tread: 4 plies nylon and sidewall: 2 plies nylon cord The hole spacing appears to be 5 on 4 1/2. Can you set me up with a good tire? Is radial better than a bias ply? The boat is heavy and I would rather move up in tire grade than down. I will probably buy two tires and wheels and keep one of the ones I have for a spare.

asked by: Shane H

Expert Reply:

Radial tires are superior to bias-ply tires. The main difference between a radial ply and a bias ply tire is how the tire is constructed. The cords inside a bias ply tire run at a 32 degree angle to the direction of travel, and the cords on a radial tire run at a 90 degree angle to the direction of travel, or across the tire from wheel lip to wheel lip.

A radial tire flexes more than a bias tire, giving it better ground contact, traction, stability, and tread wear.

A radial tire will normally run cooler than a bias ply tire, especially when the tire is under a load. A tire that runs cooler will last longer.

For a modern size equivalent tire size to the 78-14 that you have you would want the tire size of ST205/75D14. For a wheel and tire combo that has a 5 on 4-1/2 inch bolt pattern you would want the part # AM3S455. This is a Load Range C setup that has a 1760 lbs at 50 psi. Trailer tires should always be inflated to their max psi to get the full capacity.

expert reply by: Jameson C