2008 Jeep Patriot - One tire wrong size

A little over four months ago, I had a flat tire replaced on my 2008 Jeep Patriot. On the way I home I noticed a vibration around 35-40 mph. There was also an occasional “thunk” from somewhere underneath the vehicle. I took it back to the tire store 2-3 days later, and they rebalanced the tires. No help. Took it back again again a couple of weeks later, and they could not find the problem. They recommended I take it to a dealer. It was a month or so before I could get it in to the dealer, and they replaced some worn parts in the drive train. (Sorry, I don’t recall exactly what they replaced; I’m an idiot at this stuff.) Still the vibration. Took it back to the dealer, by now about 4 months after the tire was replaced, and after having it in the shop for two days, they finally noticed that the replacement tire was the wrong size – didn’t match the mfr specs and (probably more importantly) didn’t match the other three tires. They replaced all four tires, which were now worn and worn unevenly. The replaced the rear toe adjusters and one lower control arm. And alligned it, of course. Total bill for all the work done by the dealer, including the orignial work and the new tires, is pushing $2500. Originally, the dealer blamed the worn toe adjusters and lower control arm on the wrong-sized tire, but once I started asking them for information to use against the tire dealer, they crawfished and said the only thing that the tire dealer should be responsible for was the tires and alignment. I took the vehicle and the old tires back to the tire dealer and asked them to refund what I paid for the replacement tire, pay me a prorated portion of the replacement for the other three tires, and pay for the alignment. (Which I thought was very reasonable.) They haven’t given me an answer yet, but the manager claims that having one wrong-sized tire would not affect the other tires, that the uneven wear on those tires was caused by the worn parts that the dealer replaced (toe adjusters and lower control arm).

So how much of the damage could have been caused by the wrong-sized tire?

Please state the sizes of all tires involved and the location of the “wrong” tire on the vehicle. Also, what type of 4 wheel drive does it have?

The thunk & vibrations was your differentials trying to release pressure due to mismatch in speeds. AWD vehicles do not like massive changes in rotational speed. They can take some but constantly creates excessive wear.

You may be facing AWD damage down the road.

We can provide more help after you answer Insightful’s questions…

The vehicle had four tires sized P215/65R17. A flat on the right rear was replaced with a P215/60R17. It is equipped with Jeep’s “Freedom Drive II Off-Road Package,” which includes a continuously variable automatic transaxle and “active four-wheel drive” or “full time, on demand, four wheel drive” which (as I understand it) means that normally only the front axle is engaged with the rear axle engaging when certain conditions are detected (such as the front wheels losing traction or a change of grade). It also has a 4WD lock, which locks the center coupling so that both axles are always engaged, but I doubt that has been used since the flat tire was changed.

The diameter difference is 0.8 inches and the circumference difference is about 2.5 inches. Even with some wear on the old tires, the diameter and circumference differences should still be significant. Discuss this with the dealer or another knowledgeable mechanic and get an opinion on possible damage to your drive train.

Oh, I’m quite sure the dealer found already found all the damage that he believes exists. Did I mention I’ve paid the dealer close to $2500?

But back to my original question: How much of the damage was caused by the mismatched tire?

I absolutely agree that the tire size difference probably caused premature wear to the 4WD system. The trouble is that on an 8 year old vehicle it’s going to be pretty much impossible to determine how much of the wear was tire caused and how much was just age related. It could be that the parts that were changed would have worn out in another six months anyway.

I think you’re going to be stuck “writing off” the $2500 as the cost of an education in tire sizes and 4WD systems and just move on. Sorry, I wish I had a better suggestion.

And to answer Mirsm’s question:

I think (and this the consensus from the thread seems to confirm) that what Mirsm’s paid for repairs was NOT associated with the difference in tire size. If there was any damage, it was to the drivetrain that has yet to fail - and with an 8 year old vehicle, it would be very difficult to point to this incident as a cause of a driveline failure several years from now.

Now that I’ve seen the worn parts that the dealer removed, there’s even more evidence to support the group’s consensus. They really look like the result of long term wear (despite my lack of knowledge of automobile mechanics, I do know something about metals and corrosion).

BTW, my biggest worry is whether there’s damage to the transmission. I’ve never been very confident in the CVT. But as you say, the Jeep has 8 years (and 100,000 miles) on it, so if there’s been any damage to anything that is yet to show up, I’ll never know if or how much this tire contributed.

Thanks to all for your help!!