If you’re like me, uneven trailer tire wear feels like theft. It’s not fair. One side of the tire is in the prime of its life, and the other is eating through a straw and watching Family Feud reruns. When an RV tire wears unevenly, it wears faster, and you pay the early price.
So what causes uneven trailer tire wear? In particular, what if your travel trailer or 5th-wheel tires are wearing on the inside only?
Reason 1: Your Tires Are Underinflated
Any time you see uneven tire wear, check your inflation first. You’d be amazed what problems under- or over-inflation can cause, even tire blowouts!
However, wear on both sides of the tire is a more common indicator of underinflated tires. If you’re only seeing wear on one side, you might have another problem. But still, check your inflation pressure first.
Solution: Generally, I recommend inflating to the maximum cold inflation pressure on the sidewall of your tires. Or refer to the Tire and Loading Information decal sticker.
Reason 2: Your Trailer Is Overloaded
Travel trailer tire wear on the inside often indicates a heavily loaded or overloaded RV. The heavier an RV, the more the tires will tend to lean inward at the top (this is called negative camber), and this causes the inside to wear faster.
Why is this? Well, if you’ve ever peeked at the axle beneath a trailer, you’ll notice that it’s not straight. It’s curved upward, with a bend in the middle. That’s intentional. As the trailer is loaded, the axle should straighten out, and the tire camber should equalize. (And if you see that your axle is bowed downward, that’s a serious sign of a damaged or worn-out axle).
Solution: Have you weighed your RV recently and compared its loaded weight to its GVWR? Better yet, have you compared the actual axle weight to its GAWR? If you’re constantly loading your axle to its maximum and driving long distances, then I would expect uneven trailer tire wear. You need to lighten up!
Reason 3: Your Axle Is Damaged
As I said, your axle should have a slight curve upward when the trailer is partially loaded. If your axle curves downward or shows signs of impact, like dents or cracks, then you might need to repair or replace your axle. You might have hit a speed bump, rock, roadkill, or a pothole in downtown Chicago.
Solution: Tow your RV to a reputable truck n’ trailer service center. If they agree that a damaged axle is the problem, they’ll need to special-order a replacement. In some cases, if the damage is minor, they might fix the alignment problem simply by “re-bending” the axle. Contrary to what you might see on YouTube, this is NOT something you want to try at home with a bottle jack!
Reason 4: Your Suspension Was Installed Out of Alignment
I use the term “alignment” very specifically here. When talking about a passenger car alignment, we’re usually talking about caster, camber, toe, and thrust. For instance, if you’ve ever driven a car that pulled to the right or left, you probably needed a toe alignment.
Most RV suspensions – leaf spring or torsion axle – cannot be aligned like passenger cars. They aren’t that smart. They do not have field-adjustable camber, caster, and toe angles. They are what they are. When these suspension components wear out, you don’t adjust them; you replace them.
(This is not true for more advanced trailer suspensions on off-road campers, like the Timbren Axle-Less system. And at one point, Lippert had a Correct Track system designed for use with a measuring laser, but the system fell out of favor with repair shops and has since been discontinued.)
However, you can check the tracking. This is similar to the thrust angle of a car or motorhome. You’re making sure that the axle is perpendicular to the direction of forward travel. If it isn’t, the camper will veer left or right, wearing down the inside of one tire more than the other.
Somewhat confusingly, the axle[s] on a trailer should be perpendicular to an imaginary line from the coupler/king pin, not necessarily to the frame. So the track is measured from the center of each tire (or another convenient datum, like the hubcaps) to the center of the ball coupler or king pin.
If the axle was installed properly, the distances for left and right tires should be equal (or within ⅛” of each other). If the distances are NOT equal, then the factory may have welded the axle hangers in the wrong location. It happens more often than you might think.
Solution: This problem is neither easy to diagnose nor fix yourself. You need professional help, and in many cases, the hangers will need to be re-welded to the frame or reinforced.
Hot Hint: Wear across the tread indicates a camber problem. Wear at the corner of the tire indicates a toe problem.
Reason 5: Your Suspension Parts Are Wearing out
As your suspension ages, it will fall out of spec. For instance, bushings on leaf spring suspensions and rubber cords inside torsion axles are often the first components to give up the ghost. Bushings can be replaced; rubber cords cannot.
Other possible worn-out suspension components include:
- Bent spindle
- Worn-out wheel bearings
- Bent wheel rim
- Leaf spring eye bushings
- Broken axle spring seats
- Equalizer links
Solution: Your bearings should be serviced and inspected as part of your annual RV maintenance. They are fairly cheap and easy to replace, as are eye bushings. Any qualified RV mechanic should be able to diagnose the condition of these parts.
Reason 6: Your Spring Hangers Need Reinforcing
Technically, this should be Reason 5b, but my OCD won’t allow it.
As you probably know, most towable RVs use leaf spring suspensions, where a tube axle is fastened to leaf spring bundles which are connected to spring hangers welded or bolted to the chassis frame.
Those spring hangers take a lot of abuse. In severe cases, deformed spring hangers can cause uneven tire wear.
Solution: A common upgrade is to reinforce the spring hangers with v-braces, fish plates, gussets, or aftermarket add-ons like the MoRyde X-Factor crossmember. These prevent fore-and-aft and side-to-side movement.
This is not a DIY job. If you weld the reinforcements incorrectly, you’ll likely worsen the problem, not fix it. So find a qualified truck n’ trailer repair shop or RV service center.