Boat owners can get away with a rusty and dilapidated boat trailer — though they shouldn’t — but the trailer won’t move an inch if its tires fail. And here’s something to remember about maintaining trailer tires: just kicking them won’t reveal a darn thing. Unless your boot goes through the tire! We have 12 tips for maintaining trailer tires.
1. First, make sure the tires are right for the job. Boat trailers should ride on tires marked either “ST” or “Trailer Use Only.” That’s because the sidewalls are stronger, to carry the weight of the boat, especially during turns. Be sure the load range for the tires is correct for the boat and trailer weight.
2. The first indicator of a problem is often unusual tire wear, either in the center or along the edges (called “feathering”). Tire pressure that is too high will cause the center of the tire to wear quickly, while low tire pressure is indicated by wear on the side of the tires, although this can also mean an alignment problem (see #3). To find the correct tire pressure, look at the markings on the sidewall of each tire to see what the proper pressure is when cold (the trailer hasn’t moved) or hot (even a drive around the block). Get a good tire-pressure gauge or install a wireless tire-pressure indicator that provides the PSI of every tire right on the dash board of the tow vehicle.
3. Uneven tire wear can suggest problems other than over- or underinflation. If both tires are wearing on the same side, that indicates an axle alignment issue. It’s easy to fix, and will keep the trailer towing straight. If the wear is on the inside of both tires, it suggests the trailer is overloaded and the axle is flexing downward. Check the trailer’s weight rating and compare it to the boat’s weight. Don’t forget to include the weight of fuel and water: 100 gallons of water weighs 840 pounds, while the same amount of gas weighs 600 pounds.
4. Tires are just like people: They start to show wear with age. A quick glance at a tire’s sidewall may show tiny cracks, usually near the tread, which means the tire is rotting and should be replaced immediately, before a catastrophic failure. The age of a tire is indicated by the four-digit code printed on the sidewall: 0409 means the tire was made in the fourth week of 2009. Industry experts suggest trailer tires last up to five years.
5. Tire balance is just as important to a trailer as to a car, and an unbalanced trailer can pound itself to death. Make sure the trailer’s tires are professionally balanced.
6. Tire wear is a natural event, but make sure tires have the proper tread depth. Place a Lincoln penny upside down in the tread. If the top of the president’s head is showing, it’s time to replace the tire.
7. Check the sidewalls for any bulges or lumps, which are clear indicators of a cord (carcass) failure or perhaps a break from a side impact. Replace the tire immediately.
8. The valve stem on tires is often the culprit in the case of a slow leak. To test it, use your finger to push the stem to the side and listen for a hissing sound. If you hear the sound, it’s time for new valve stems all around.
9. Trailers face enemies even when they aren’t on the road. The first — and worst — is sunlight. The UV rays of the sun will oxidize tires, causing the sidewall to crack and fail, which is why so many boat trailers (and RVs) are stored with covers over the tires. Tire covers are available cheap at an auto supply store (or they’re an easy DIY project).
10. Surprisingly, tires aren’t completely waterproof, so long-term storage on grass can allow water to penetrate the tire surface and cause all sorts of problems. If possible, park the trailer on concrete or even pads of plywood. Or simply remove the tires to protect them from sun, water and theft.
11. Trailer tires left to sit for a long period, especially with the load of the boat, can develop flat spots, which cause high wear and are hard on the boat and trailer, because they pound along on the highway. If the boat will be idle for an extended period, jack up the axle and put concrete blocks underneath to lift the tires off the ground.
12. You’re going to hate me for this one, but speed causes increased wear. Most trailer tires are rated for 65 mph, but in reality we all hit 70 mph or more on open stretches. Don’t even think about driving at higher speeds unless you’ve checked the tires carefully and they are inflated properly. Keep in mind that tire pressure will change by one pound of pressure with every 10 degrees of air temperature. If you set the tire pressure on a 50-degree morning, the tires will have increased by five pounds of pressure during a trip to a desert lake on a 100-degree afternoon. Check regularly to make sure the tires are inflated to the right pressure.
Spend as much time taking care of the trailer tires as the boat, and you’ll never spend any time sitting by the roadside.