Trailer and Tire Do’s and Don’ts: Answers to Common Questions
Whether you’re towing a camper, a boat or a cargo trailer, whatever’s attached to your hitch needs the same attention your vehicle gets. If you’ve noticed uneven tire wear, your trailer is bouncing or you’re not sure what type of tire is best, here’s a quick FAQ.
1. Is It Okay for the Rear of My Truck to Sag When It’s Hitched to My Trailer?
You don’t want your tow vehicle to sag under the weight of your trailer. It means there’s not enough weight distributed to the front wheels of your truck or SUV and it will compromise your handling. You’ll also create uneven wear on all your tires, and they won’t last as long as they should.
If the trailer tongue isn’t within an inch or two of being level with the ground, you need to make some adjustments.
There are many approaches to fixing an unlevel tow issue, depending on your rig:
- Adjust your trailer mount up or down to get the proper rise or drop.
- Rearrange your load. You want about 10 to 15 percent of the fully loaded trailer’s weight placed on the trailer tongue. (Determine tongue weight, the weight a fully loaded trailer exerts downward on the hitch ball of the tow vehicle.)
- Add airbags to the suspension of your tow vehicle. This lifts up the rear and puts more weight on the front, evening out the load.
- Add helper springs to your tow vehicle.
- Use weight distribution hitches with spring bars.
2. Is It OK to Mount Non-trailer Tires on My Travel Trailer or Should I Get Special Trailer Tires?
ST (Special Trailer) tires are a better choice. Non-trailer tires are made to carry people. ST tires are designed for carrying the heavy-duty load of travel and other trailers.
Structurally, STs have straight, solid ribs—the ribs being the circumferential bands of strong rubber separated by grooves. This makes them suited to bear heavier loads. They have about 10 percent more load capacity than light truck (LT) tires of the same size and 40 percent more than an equivalent passenger tire.
The stiffer sidewalls on ST tires improve stability and reduce swaying. These tires are usually narrower to fit standard trailer wheels. They're designed with shallower grooves to improve fuel economy and help them run cooler, since hauling loads can generate a lot of tire heat.
Non-trailer tires have lots of voids and deeper grooves on the tread to evacuate water quickly for better traction. The ribs are often jagged and separated by grooves.
3. My Trailer Is Bouncing When Underway. What’s the Problem?
Any trailer hauled without its load will bounce. Boat trailers, for example, are made with stiff, solid axles with loose springs, which causes them to jump a lot when not weighed down.
If your trailer still bounces while loaded, there could be other issues that need attention:
- Your tires aren’t properly inflated.
- Your tow vehicle’s shocks are worn or aren’t designed for the load. (You’ll feel bouncing that continues after going over a bump).
- You need to shift the weight inside the trailer.
- The trailer is overloaded and the suspension could be damaged.
- One of the trailer axles might be damaged.
- You’re not towing level (see question 1).
4. What’s Causing Uneven Wear on My Trailer Tires?
Generally, trailer tires don’t wear evenly: It’s just physics. When a tandem axle trailer with four tires takes a tight turn, the inside tires will “slide” a bit rather than roll, because they have significantly less distance to travel. Over time, this scuffs off tiny parts of the tread, creating odd wear patterns.
That said, rapid or significantly uneven trailer tire wear can be caused by:
- Riding with the wrong tire pressure.
- Exceeding your tires’ load capacity.
- Trailer misalignment or bent wheels from hitting curbs, potholes or debris.
- Not towing level, which puts more weight and strain on one axle.
- Uneven load management instead of spreading weight evenly to all wheels/tires.
If all four tires are wearing heavily on the inside, the trailer is probably overloaded.
Trailer axles are built with a slight upward curve in the middle. When the trailer is unloaded, the tops of the tires lean slightly outward (toed-out, or duck-footed). When they are carrying the weight of whatever’s loaded, the axles straighten to a flat position and the tires come to a straight up-and-down position.
When the load is too heavy, the axle bows downward in the middle, causing the tires to roll pigeon-toed (more on the inside shoulder of the tires). That’s not the normal contact patch for tires, and you’ll see pronounced wear there.
Another possibility is the axle has been flipped over (the bow in the axle that is supposed to be pointed up is actually pointed down).
If only one tire is wearing faster on the inside, you may have a bent suspension part, like a spindle. This can cause one tire to skid rather than roll smoothly down the road, creating heat and friction that wears out the rubber.
If you see faster wear on the outer tread, this may be a case of an under-loaded trailer: The trailer weight is too light to straighten out the axle. Or, outer tread wear on just one side may be a symptom of a worn suspension component.
>If you notice tire cupping — a bulge on one area of the tire — the belts or plies inside (the strong cords of steel and nylon that give the tire its strength) are failing. It can be caused by tires that haven’t been properly balanced, wheel bearing problems, bad alignment or something worn out in your suspension. It can also result from excessive heat caused by going over the speed rating of your tires.
Tires on a trailer parked for a long time can develop flattened spots in the area that contacts the ground. To prevent this, simply move your trailer regularly.
Find out how to keep your trailer tires in the best condition possible in our post, 8 Great Ways to Get the Most from Your Trailer Tires.
How to Have a Happy, Safe Summer Road Trip
So you’re hitting the road for your favorite campsite, fishing hole, theme park or beach rental. Here are 17 summer driving reminders to keep you, your passengers and fellow travelers safer on highways and byways.
- Make sure your vehicle is safe and road-ready with this checklist.
- Buckle up every time.
- Put kids 13 and younger in the back seat. No exceptions.
- Inflate tires properly. Proper inflation is important for safety and can save you up to 9 cents per gallon through better fuel efficiency.
- If you’re hauling, use a safety chain for trailers and inspect your hitch whenever you stop.
- Check blind zones before backing up. Trucks, SUVs, RVs and vans are more likely than cars to be involved in backovers.
- Remember to add clearance for trailers, campers, bike racks and roof racks. It’s easy to forget your extra height or length.
- Add following distance. A fully loaded vehicle needs more stopping time.
- Add extra following distance for motorcycles. They can stop much quicker, in shorter distances.
- Slow down if there’s a sudden cloudburst to avoid hydroplaning.
- Never leave kids or animals in an unattended car, even with windows down or A/C on.
- Lock your vehicle when exiting.
- Don’t drive distracted. Don’t text or check your phone. Check out cell phone laws by state.
- Watch for pedestrians and cyclists on the shoulder. Warm weather means there are more sharing the road.
- Before driving, don’t take medications, alcohol or drugs that will impair you.
- Pull over if you get drowsy.
- If you get stranded without a roadside assistance policy, call an on-demand roadside service.
8 Great Ways to Get the Most from Your Trailer Tires
Maintaining trailer tires isn’t always the same as what you do for passenger vehicle tires. Here are the basics on getting the longest tire life, figuring out your load range, making sure you’ve got your trailer weight calculated right and preventing tire failure.
1. Maintain the Right Trailer Tire Pressure
Running ST (Special Trailer) tires under-inflated is a sure way to quickly wear them out and invite tire failure. Keeping them at the full PSI (pounds per square inch) pressure is key for longevity, load-carrying ability, cool running and best fuel economy.
You can’t tell if trailer tires are properly inflated by eyeballing them. An under-inflated ST tire may not sag like a passenger vehicle’s because it’s built with a stiffer sidewall. Trailer tires can look fully inflated and be far below the safe PSI.
Find the proper tire pressure by looking at your tire sidewall. (The right tire pressure for passenger vehicle tires is found on the placard inside the driver’s side door.) Look for the small notation Max. Load followed by a PSI number (80 in the example below).
Trailer tire pressure should always be checked when the tire is cold, ideally before being driven that day. Driving generates heat and heat generates pressure, which will throw off your measurement. Here’s how to do it yourself.
2. Figure Out the Maximum Load for Your Trailer Tires
It’s really important not to overload trailer tires. Overloading tires can cause premature wear and increase the risk of tire failure.
The “Max. Load” information stamped on the sidewall indicates a tire’s load capacity when it’s inflated to the proper PSI. In the example, this tire can handle a maximum 2,830 pounds when it’s inflated to 80 PSI and used in a “single” application: one tire on each side of the axle.
Note: Some trailer tires are also marked with a “Max. Load Dual” number. This comes into play when two tires are mounted on both sides of the axle (four trailer tires total), a “dual” application, or dually, which is an unusual application. In the above example, each tire’s load capacity is reduced by 13 percent to 2,470 pounds when it’s used as a dually. This assures that if one of the dual tires fails, the remaining tires can keep the trailer stable until you come to a stop.
Be aware: If your tire pressure is lower than what’s recommended, the tire’s carrying capacity will be lower, too.
3. Determine the Actual Weight of Your Trailer
You just need to get tires that can support the trailer weight listed on the placard on your trailer or in your owner’s manual ... right?
Not quite. That weight figure doesn’t include all the cargo your trailer will be carrying. Get an actual weight by visiting a truck stop, feed store or gravel supply store when you’re fully loaded, including full water and propane tanks.
4. Get the Right Trailer Tire Size
Refer to the trailer placard or your owner’s manual. Either will tell you the manufacturer’s recommendation. (Trailers have a federal certification/VIN label generally located on the forward half of the driver’s side of the unit. Some trailer sizes also have a separate vehicle placard located there that describes tire and loading information.)
Or you can look at the tire sidewall sizing information. Then be sure to check with a tire professional before you buy to make sure what you have in mind is the right fit for the loads you’re hauling and roads you’re traveling.
5. Have Tires Inspected Yearly
Travel trailer and boat trailer tires sit for long stretches in one spot. The contact area of the tire that bears all the trailer weight while it’s parked can get weakened when a trailer isn’t moved for weeks on end. You should have your tires and bearings inspected every year by a tire professional.
6. Get a Spare Tire
Carrying a spare for your trailer may just save your day or vacation. Boat trailer and travel trailer tires are often specialty tires that aren’t always readily available in places where you’re recreating.
A spare tire means you’ll have an hour or so of hassle changing a tire if you get a flat, versus missing a day or more of vacation, or having to leave your trailer loaded with gear to go in search of an open tire shop.
Money-saving tip: When you replace your full set of trailer tires, consider keeping the one that’s got the least wear to use as a spare, so long as a tire professional inspects the tire and confirms it is suitable.
7. Don’t Mix and Match Radial and Bias-Ply Tires on a Travel Trailer
The trailer’s certification label or owner’s manual may give you advice on which type of tire construction is best. Some of your choice depends on the type of trailer you have and the kind of travel you're doing.
Radial tires run cooler so on longer trips they don’t wear as fast. They’re also less prone to developing flat spots when a trailer is parked in one place for weeks at a time.
Bias-ply tires have stiffer sidewalls, which can reduce trailer sway.
Whatever your choice, don’t mix-and-match tire types or sizes. Go with all radials or all bias tires.
8. Extend Tread Life Through Simple Maintenance
- Visually inspect your tires before each trip.
- Check tire pressure before you use your trailer, and every morning when the tires are cold during long trips. Keep your tires inflated to the maximum PSI branded on the sidewall.
- When you’re storing your trailer for the off-season, use tire covers to protect them from early wear. Park in a cool, dry place.
- Keep caps on tire air valve stems, to keep debris and moisture out.
- If you notice excessive, uneven trailer tire wear, get a tire professional to assess what’s going on and determine if there’s a fix.
- Don’t assume that replacing tires with a set that has a higher load capacity will fix uneven wear problems. You’ll likely have the same problem with the new set if there’s something wrong with the trailer alignment, suspension or axles.
Come on by your local Les Schwab Tires store and we’ll be glad to help.