What could be causing a bad wear pattern on the tires of a relatively new vehicle?

Dear Car Talk

Dear Car Talk | Aug 01, 1999

Dear Tom and Ray:

Our relatively new Toyota 4Runner has us stumped. While checking the tires
on a recent trip, I noticed a strange wear pattern on the two front tires.
I had the tires rotated soon after that, and the strange wear was confirmed
by the mechanic. The front tires are severely worn on the inside edge,
extending approximately 3 inches toward the center of each tire. On top of
that, the wear is not uniformly distributed. Rather, it appears as though
there is a "bumpity-bumpity-bumpity" pattern to the wear. We have had no
other trouble with the SUV, and we are in no hurry to visit the dealer --
warranty or not. Can you help us? -- Dennis

TOM: It could be any or all of the following, Dennis: bad alignment, bad
wheel balance, bad shocks or real el-cheapo tires.

RAY: And if I were you, I WOULD take it back to the dealer. While it may be
something they insist you pay for (they may argue that you knocked off the
alignment by driving it over some buildings in your new-SUV enthusiasm),
there may be something actually wrong with the truck.

TOM: If I were a betting man, I'd guess that you have toe-in and camber
problems (both alignment issues) and/or the 4Runner came with real cheap
original-equipment tires. And those would be things that you would have to
pay to fix.

RAY: But if, for some unusual reason, the car can't be aligned (if there
was a manufacturing defect, for instance), then the warranty would apply,
and you'd certainly want the dealer to take care of that for you. Good
luck, Dennis.

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