Abnormal Tire Wear
Q. I recently returned from a 5,000-mile vacation to Utah from Indiana. I towed a 26-foot travel trailer. After arriving home, I noticed abnormal tire wear on two of my four trailer tires, both on the rear axle. These tires were like new at the beginning of this trip. Both are now worn almost smooth on the extreme outside edge. Before leaving on this trip, I packed the bearings on all four wheels and the bearings were torqued correctly upon re-installation. The tire pressure was also checked and was correct. Overloading shouldn’t have been a problem because I actually removed gear from the trailer to lighten it as much as possible prior to this trip in anticipation of some mountain towing. I didn’t hit any damaging potholes or rough roads or rough railroad crossings that I can recall. I am at a loss as to what the problem could be and don’t really know where to get this type of problem examined. Can trailer axles be aligned?
– RP, Evansville, Indiana
Q. I have a ’96 Four Winds 26-foot fifth-wheel, and I recently found that all four tires are worn smooth on the inside edges, plus they are scalloped as well. From what I understand, tire wear like this can be attributed to toe-in or -out, or excess camber. It would be hard for me to believe that both axles are bent, but the exact same unusual wear pattern on all four tires is most puzzling. I suppose I can bend the axles back to zero camber and reinforce them as needed.
– MT, Eastham, Massachusetts
A. As both of you have discovered, RP and MT, there’s a lot of room for adjustment, and for being out of adjustment, with trailer axles. The axles may not be parallel, in which case they are constantly fighting each other as you drive, which obviously will grind tires away in short order. They can also be out of adjustment for camber and toe-in, and as with tow rigs, such mis-adjustment can prove disastrous for tire life. Alternately, if the trailer is riding in an extreme nose-high or nose-low attitude when towing, that can shift some load to the front or rear axle, which can also lead to uneven tire wear. Combine that with bad alignment, and it’s a double whammy.
RP, the edge wear you found seems to be from too little camber — that is, the top edge of the tire is tipped out, compared to the bottom edge, which places too much wear and weight on the tire’s outer edge. This may require having the trailer axle bent back into place, which basically means bending the center of the axle down a little to bring the tires back into alignment.
MT, your axles could have several problems, including overloading. If the trailer weight is excessive, compared to the axle’s gross axle weight rating (gawr), the leverage effect of the weight bearing on the axle causes the center of the axle to bend down, which tips the tires in and wears the inside edge. This is an extreme case, but it happens. Your situation could likely be cured, as in RP’s case, by a trip to a qualified alignment shop that knows how to work on RV trailers. It may take some searching to find one, but a qualified shop can readily get your trailer suspension back into shape, which should also have the extra benefit of improving the trailer’s towing stability. — Jeff Johnston