How Tires and Wheels Work

Choosing Tires and Wheels
No matter how much work you plan to throw at your trailer, you're going to want to make sure you have the right wheels.
No matter how much work you plan to throw at your trailer, you're going to want to make sure you have the right wheels.
David Oliver/Taxi/Getty Images

You know that trailer axles require trailer tires, but do you know what kind to buy when choosing tires and wheels? When you walk into the tire store, make sure you have all the essential information on hand so you can get rolling on your new towing venture.

Tires fall into three categories: passenger (P) tires, light truck (LT) tires and special trailer (ST) tires. You'll want to go with ST tires. Your trailer should have each axle's gross vehicle weight (GVW) listed on the body or in the owner's manual. This figure is the total amount of weight the axles can withstand, so you'll need tire capacity that meets or exceeds the GVW. If you know how much weight you plan to tow, you can be a little more exact. First, determine the weight of the unloaded trailer. Then add the weight of your payload. The combined capacity for all of the trailer's tires should exceed the total loaded weight by at least 20 percent.

­Once you've found tires that fit your weight requirements, save yourself a lot of trouble and make sure they're attached to wheels that are going to fit on your wheel hub. To avoid any frustrating revelations, know the bolt pattern for your trailer's wheel hubs. It may have four, five or even eight bolts, and you'll want your trailer tire to match up. The distances between the bolt holes, called the bolt circle, also has to be exact.

The bolt circle is the center-to-center diameter of the imaginary circle that the bolts or bolt holes outline. With even bolt numbers, simply measure the distance between two opposing holes or bolts. With odd numbers, measure the distance between a bolt or hole and the halfway point between the two opposing it. If your wheel hub has five bolt holes and the bolt circle is 4.5 inches (114.3 mm), then your wheel's bolt pattern would be 5 on 4.5.

In addition, bear in mind what kind of roads you plan to tow your trailer across. If you plan to traverse rough roads or open terrain, you might want to invest in all-terrain tires. Finally, whatever variety you wind up getting, make sure all the tires on the trailer are identical in size. If you don't, the trailer weight won't distribute evenly.

Ready to install those tires? Go to the next page to find out how.