Maybe we should be reporting excessive tire wear to Mazda
(RTM) ...remember that you bought a fairly high performance vehicle. It did not come from the factory with wimpy all season tires with a treadwear of 440. I believe the treadwear on the Potenzas is 140...i could be wrong,..but I know it is very low. It's a soft compound summer tire. Same thing happened with the stock tires on the MSP's.
There are decent performance tires out there with treadwear in the 300 range. Tirerack and discounttiredirect shows the specs of tires online.
There is nothing wrong with your tires. As a previous Toyota service manager I heard that complaint many many times from new car owners. Especially those buying a car like the camry se v6. Those buying a camry are not looking for performance tires but from the factory they were coming with a fairly soft compound. 15K miles into the car they would start complaining when they needed new tires.
Bottom line,...you are lucky to be driving a MS6! Now go buy a longer life performance tire.
My experience tells me that the writer quoted above is correct in that there is nothing wrong with the tires, but I disagree with his contention that buying tires with a high treadwear number is the answer. I believe that there is something mis-engineered with the front suspension of the Speed6. I have read that a camber adjustment could cure the problem of uneven and premature tire wear, but the camber is not adjustable; however, I don't know how accurate that report is.
As for my experience, a month after I bought my Speed6 in November 2006, I was in a light snow and (despite my dealer's testimony when I questioned why Mazda would sell a car in Pennsylvania with only
summer tires) I found the "stock" summer performance tires to be totally unsafe. At that point, I installed Pirelli P-Zero Nero Mud and Snows, rated at 400. By the time they had 15,000 miles on them, they were worn to the point that they would not pass a PA state inspection.
At 5,000 miles, I took the car to the dealer believing that the front end was way out of whack because the outside edges of the front tires were cupping badly and the inside edges wearing noticeably. The dealer was alarmed enough to check the alignment--free. The report came back that all was in spec, and the dealer rotated the tires front to rear and added two pounds of pressure. At about 12,000 the "new fronts" were not cupping as badly as the originals, but still wearing alarmingly quickly, so I visited the dealer again. Once again the service manager was concerned enough to re-check the alignment--again free, so you know they had to figure that something was wrong with my car!--and it came out fine again. I made a third visit a couple of weeks ago with the tires worn beyond inspection standards, and I was basically told that I have a performance car with performance tires, what did I expect? Rotate them with each oil change, and GO AWAY.
The change in attitude makes me believe that, as Mazda dealerships are becoming more familiar with the cars and getting a parade of them coming in for the same reason, they are coming to realize that this is a common condition and unfixable.
If you go to Tire Rack web site and check the reviews, you'll see that people are getting in excess of 60,000 miles out of these Pirellis, and one of the guys I work with has a Lexus 300 with 50,000 miles on his P-Zero Nero M&S's, so it's not the tires. I don't drive overly hard. I put two sets of replacement tires (one at about 40,000 miles and another at 90,000) on my last car, a Nissan Maxima, and sold it at 130,000 miles with plenty of tread on the tires, so I don't think it's me. That leaves only the car.
I really love the Speed6, but I won't put up with putting tires on it every 15-20,000 miles. I'm going to give it one more shot with a harder Yokohama Avid H4s (500 wear rating) and, if these don't last more than 20,000 miles, I'm going to put the almost unused summer tires back on it and trade it.
Perhaps everyone with this problem should call Mazda at 800-222-5500 and complain. If you do, have your VIN and other pertinent info handy.