Could one smaller tire on back be the cause for the rear wheel bearing to go out on a subaru outback?

Question

I got a new tire after it was popped, and around 1 months later I got the other three tires replaced. All was fine the shop said, the tread on the one tire replaced a month earlier was fine.

After driving a few weeks, highway use mostly, I felt my steering wheel shake. I made an observation and noticed that three of my lug nuts had broken off. I returned to the shop where they took full responsibility for the mishap and promptly fixed the problem. The kid who had changed the tire was new and didn't quite know what he was doing when it came to the torque of the lug nuts.

So about a month later, I was starting to hear a wrr wrr wrr wrr noise. Not being a mechanic, I shrugged it off. Then it started really making noise so I stopped by the shop where they checked it out and came to the conclusion that I needed front brakes. When I was able to afford it, I got my front brakes done by a friendly young man who had done his fare share of brake jobs. When he was finished replacing the front brakes, he noticed that my left rear tire was smaller than the other three.

So again I took it to the shop where they again took full responsibility for the problem, and again they fixed the problem by changing out the smaller tire with the correct size tire. At that time I asked them if having the wrong size tire would have caused any damages to my car??? They replied with a definite NO. Again I drove off happy I didn't have to pay for anything.

But still this wrr wrr wrr wrr noise continued to get louder and louder but after 6 months of this noise a wobble started. So here yet again I find myself back at the shop asking them what's the problem???? They checked it out and said it was my rear wheel bearings....yes both rear wheel bearings.

Now mind you they had been replaced in 2012 so I didn't figure they were ready for them to be replaced quite this soon, but who am I to question ???? RIGHT... Well I'll tell you I am not stupid when it comes to commonsense, but it seems a little off that the sequence of events were as they are. So if anyone can explain to me if what I am thinking is either correct or totally wrong in my assumption that my rear wheel bearings went bad due to the fault of the wrong tires being put on my car.

Oh yeah if I didn't mention I have a 1999 Subaru Impreza outback. Thank you for your opinion in this matter.

Answer 1

One tire with a months usage more than the other three will not be a cause of any issues. If you have a tire that is substantially different in circumference to the others, that's bad (which is why all four are generally changed at the same time) - but the damage is usually related to the differentials, not to the wheel bearings. Your tire did NOT cause the problem.

Now, to the actual problem. Subaru's do eat wheel bearings - especially the rear passenger bearing (no, no idea why, but that's always the first to go :) ). The bearings are a press-fit, and if they are not installed perfectly square, you can run through a bearing in less than 20,000 miles. My suspicions would be that the original (2012) installation of the bearings wasn't 100%.

If the bearings are so bad that there is a visible wobble, I'd get them replaced as soon as possible. Use ONLY the Subaru OEM bearings - if you have to pay a garage to install them, most of the cost will be labor, so a couple of extra dollars getting the best bearing is well worth it.