Tires
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. - J.J.
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