Can a 4.80-12 Bias Ply Trailer Tire Be Used in Place of a 145/80R12 Radial Trailer Tire  

Question:

Expert Reply:

The tire size you have is likely a 145/80-12. This size is 21.3 inches in diameter and 5.7 inches wide.

A 4.80-12 tire is shorter at 20.5 inches in diameter and more narrow at 4.9 inches wide.

You can go to the smaller size tire if you want, both sizes fit the same wheel, but the 4.80-12 tires have a lower capacity. At most a 4.80-12 tire will have a 990 pound capacity at 90 psi.

By comparison a 145/80-12 tire will be rated at 1,220 pounds at 65 psi. I have included some helpful links to our tire articles. Below is a section I copied from one of them comparing radial and 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.

A bias ply tire has a stiffer sidewall than a radial, a feature that might be useful for off road applications like farm use. At one time radials were more expensive than bias ply tires, but now they are closer in price. This makes radials a much better value.

expert reply by: Michael H

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