modern fishing law

11 Things To Know About Boat Trailer Tires

By Pat Piper via

Tires aren’t exciting, until something goes wrong. Then, tires become the topic of the day. Here are some tire basics so that your tires will always be, well, tiresome.

Trailer Made

Trailer tires are either bias ply or radial. Bias-ply sidewalls are stiffer, less expensive than radials, and are preferred if the trailer isn’t used for long trips. If you take long trips, then radials are a better choice because there’s reduced heat buildup as compared to bias ply, greater load capacity, and less road noise. Use all bias ply or all radials; never mix them.


Check inflation prior to going on the road when the tires are cold. The tire pressure measured in pounds per square inch (psi) will increase as the tire heats up when used. BoatUS TRAILER ASSIST service providers say tires are the main reason they’re called to help members experiencing trouble on the road. Under inflation is the cause of most tire trouble because temperatures increase when the tire pressure is too low. So, check inflation prior to going on the road. It’s marked on your tire. Remember, boat trailer tires typically need to be inflated to higher psi than tow vehicle tires. And be sure to also check the psi of the spare tire.

Load Range

How Old R U?

Your tire’s age (whether for a boat trailer, truck, or passenger car) has a DOT (Department of Transportation) time stamp that provides the tire’s date of manufacture. The last four digits tell you everything you need to know. In this example, the tire was manufactured in the second week of 2008.

Photo of a DOT tire date stamp

What Does It Mean?


This tire is designed for a trailer.


Width of the tire in millimeters.


The ratio of height to width. In this example, the tire’s height is 75 percent of its width. The smaller the aspect ratio, the wider the tire in relation to height.


This indicates a bias ply tire.”D” stands for diagonal. “R” would mean this is a radial tire.


Wheel diameter: This trailer has 14″ rims.


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