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Changing Boat Tires From Size 5.30-12 to Size 175/80R13


I have to replace the axle on my Trail Star boat trailer. Original tires/wheels were 5.3 x 12 Bias Ply. Would rather go with a 13inch wheel and 175/80/13 Radial tires. As long as I have the extra clearance, do you think it is a good idea??


Helpful Expert Reply:

Provided that you have enough clearance, changing from your Bias 5.30-12 size tire, like part # AM30859, to a Radial 175/80R13, like part # AM31994, could definitely have its advantages and is a good idea.

Bias tires are designed for more of an off-road application, like farm use, because they have a much more rigid sidewall. A Radial tire is built so that it has little bit of flex in it to help make the ride a little smoother plus it runs cooler than a Bias.

To ensure that the bigger size tire will fit you will want to make sure that there is 4-5 inches of space between the tire and any fender that you have, and then at the minimum 2 inches between another tire (for tandem axle trailer) or the sides of the fender. Your 5.30-12 size tire has a diameter of 21.9 inches and the new 175/80R13 size tire will have a diameter of 24.1 inches meaning that it will be 1 inch closer to any fender or tire. You will also want to make sure that the bole pattern on your wheel matches that of your new axle. The part # AM31994 that I referenced comes with a wheel that uses a 5 on 4-1/2 inch bolt pattern.

I have also attached a link to our selection of axles that you can look through for a correct fit. If you are wanting to go with a standard axle then you will want to make sure that it is the correct length and that the hub-face-to-hub-face (A) and the center of the spring seats (B) have the correct measurements as well (see attached picture).

A great way to eliminate a lot of the measuring and adjusting that accompanies the installation of a standard axle is to go with a set of our Timbern Axle-Less Suspension systems instead. They are much easier to install and they help improve ground clearance as well. They are included in the link for the axles.

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helpful expert reply by:
Jon G

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