Reader asks: “Fifth wheel tires wearing unevenly. Why?”

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Dear Mark,
My fifth wheel has approximately 10,000 miles on it. I’ve noticed that the tires on the rear axle are wearing unevenly on the inside. What causes this? —Gary Melton

Dear Gary,

Uneven tread wear has many causes. They are:

• Too much weight over the axle: Too much weight over the axle will cause it to be bowed down in the middle due to the excess weight, and that will change the tire camber. Your axles have a maximum weight rating on a sticker on the axle. Refer to that sticker and have your trailer weighed at a CAT scale near you to determine if your axles are overloaded.

• A broken axle: Hitting a curb, large road debris, or a large pothole can cause an axle spindle to bend, which will result in abnormal tire wear. Axles also have a slight bend in them at the center. If an axle has lost it’s bend, it is also considered broken. A broken axle must be replaced.

• Axle being out of alignment: If your axles weren’t installed square with the chassis or parallel to each other, the tires are scrubbing as you tow the trailer down the highway. Misalignment can also be caused by worn bushings in the suspension. You can determine if it is an alignment issue by running your hand back and forth over the worn area. If the tread feels smooth in one direction and sharp in the other, you most likely have an alignment problem. A commercial alignment shop can correct an alignment problem for you.

• Tires not being inflated properly:  If you have a balding center area on one or more tires, the tires are overinflated. Balding outer edges mean they are underinflated. For proper inflation, refer to the sidewall of the tire for the max PSI rating and inflate them to that number when the tires are cold.

Mark Gorrie has been an avid RVer since 2003 and owns RVForce LLC, a full-service mobile and shop-based RV repair facility based in Winter Haven, Florida. RVForce has a full team of certified technicians on staff to answer your RV questions. Email them to support@rvforce.com .

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Fred
3 months ago

You forgot to mention the effect of tire scrubbing from making sharp turns. Dual axle trailers will have slightly less or more weight on 1 of the axles than the other, depending on how level your rv is when going down the road. The heavier of the 2 axles will roll normally while making a sharp turn, but the lighter of the axles will “scrub” instead of rolling thru the turn & leave black streaks on the road. This scrubbing action takes place with any turn no matter how small, but the effect on the tires is minimal unless the turn is at a sharp angle. Then you lose a lot of rubber & because the tires are severely torqued during a tight turn, the rubber is pealed off of one edge or the other. I’m not an expert, but I would think that carrying closer to the maximum tire pressure, which balloons the tire & creates more road contact pressure on the center of the tire, would lessen the scrubbing effect on the edges of the tire.