Abnormal Tire Wear

Maintenance/Repairs
1 
I have a 2005 Toyota RAV 4, 2-wheel drive with automatic transmission, current mileage about 60,000.  All maintenance has been performed as prescribed on a regular basis by my Toyota dealer.  This maintenance included periodic wheel balancing, tire rotation, check of tire inflation (32 psig) and wheel alignment.  The vehicle is equipped with manufacturer installed Toyo radial, ?Tranpath?, A14 tires.


At about 30,000 miles, I began to notice a noise that seemed to originate at the real tires, particularly the left one. The noise can best be described as a ?rumble? that changes to some extent with speed. On examination, the Toyota service manager found that the rear tires were ?cupping?. Since all service maintenance had been performed, he had no explanation for the tire wear. He mentioned that he had not seen this in any other RAV4s.

On a following service visit the cupping appeared worse and the service manager kindly offered to replace all four tires for me at no cost; but the tires needed to be the same brand and style. Upon replacement, the noise immediately disappeared!

After about 10,000 additional miles, the noise in the rear tires returned and cupping could again be seen. I have been assured that the cupping is not a safety problem so I am driving the vehicle with this problem. Although I don?t like the noise.

Now, the question is, what is causing this cupping problem and how can I prevent it from happening again when I ultimately need to replace the current tires?

2

Tire cupping is caused by worn suspension parts (wheel bearing, shocks/struts, etc.), unbalanced tire (which doesn’t seem likely in your case) or a rear tire out of alignment. Given the age of your vehicle, I’m going to go with the misaligned rear tire. It’s probably too new to exhibit major suspension wear, but it’s not impossible for the rear tire to come out of alignment. I also wouldn’t put it past the dealership to not check the rear alignment.

3

Usually I don’t recommend random parts replacement, but I have had rear shocks wear out before 60K miles, on a Toyota Corolla. Since you can get Monroe Sensa-Trac life warranted shocks for only $40 each (before shop markup), I would replace them out now, and also get a four wheel alignment. I would have an independent shop do this work. Excellent alignment guys don’t all work at dealerships and as lproctor said, they may be missing the rear tire alignment piece. Another 10K miles or sooner will tell you if this fixed the issue or not.