Bad tire - big problem

Took the Legacy to the Eager Beaver Car Wash - best in the area. When the car was finished, the wiper boss called me over and showed me a small bulge in the right rear sidewall. Said it could be a problem if the tire blows. I called my local shop and ordered an exact replacement Goodyear Eagle LS2. I then Googled Subaru and AWD tires and found out that if more than 1/4" difference in tire circumference in even one tire, the center differential (actually a group of clutches) will definitely be ruined and have to be replaced at BIG cost. The other 3 have about 28K miles on them and the left rear has slightly less tread. Ironically, the same thing happened to my daughter's Crosstrek and she had to replace all 4. (Her lease is up in April). Since I have no way to measure the tires and no one down here shaves tires, plus my lease is ending May 11th, it looks like I'll be on the hook for 3 more Eagles at around $150 each. Since they measure the tires at the end of the lease anyway, and since I don't want it on my conscience if someone buys the car and has a bad crash due to the problem, I'm taking the car to the local dealer - I have to change the oil anyway - and have him measure the tires. I'm not optimistic. LBC owners be glad you don't have this problem, although you should not mix tires for handling purposes, but had I known of this before opting for an AWD car, I might have chosen differently. The only leverage I might have is if I choose to lease another Legacy and they might waive the cost of the new tires (or just ignore the problem and fob the car off on some unsuspecting buyer). Has any other AWD or 4WD owner here had a similar problem?

Wow seems a little over the top
Wonder how may are distroyed by a under inflated tire 1/4”
I’ve always thought Subaru as a pretty tuff set of wheels is this some new thing ?
driving in areas with roundabouts must fill up the Subaru dealership garage

This is why you have to change two tires not only one. Had a Jeep years ago and if two different size tires on rear were run long enough the rear end gears would lock up

A couple of thoughts.

1. look for a used tire (tires) they need to get you to May.

2. I suspect with careful driving the bulge will make it to May at which point it becoomes the dealer's problem. This sounds careless but it isn't any dealer worth his/ her salt will check any car before being re-sold.

3. This is normal wear and tear (or possibly a flaw) but not the kind of damage they look for at the end of a lease. They are looking for cigarette burns and dents.

4. While you obviously don't want to risk a huge expense, there are enough idjits hooning around in their Subbies around here to make me thank that none of them would be on the road if this condition was that dire.

I guess my point is, take a breath and there may be honest and viable solutions. Shoot you could return it early for the sake of 69 days. Swallowing one or two payments might be easier than having to make the payments AND put on new tires.

PS don't have the dealer measure the treads.

Or...Buy a thread depth gauge...they're $5 or so...then purchase the Goodyear ls2 from Tire Rack and pay their $25-$35 charge to shave the tire to match.

Jay has the right idea.

You could use a coin (or similar) to measure existing tread depth: put a penny in the (used) tire tread, mark the top of the tire. Then compare this depth to the tread depth on a new tire.

Doing a quick Google search on "Goodyear Eagle LS2 tread depth", it seems the depth of a new tire varies from 0.28" to 0.34", depending on tire size. Specifics here: https://www.goodyear.com/en-US/tires/eagle-ls-2/sizes-specs

Note, the maximum difference is stated as circumference (1/4"). Given circumference = pi*D, depending on the size of the wheel you could calculate the difference in tread depth to see what results in 1/4". (For a 20" outside diameter tire, the result is 2.5/64"... not very much!)

Alternately, one site claims the delta in tread depth needs to be less than 2/32". (A google search lead me to this page: https://www.souzastireservice.com/tires-101/tire-matching-awd-4wd.aspx. It is from someone who sells tires, so perhaps a bit draconian.)

Or roughly, if the existing tires are more than 25% worn, you need four new tires.

(I am an engineer... sorry for the geometric tangent.)

Another question is, how badly and how quickly does the differential break? (What is the failure mode?) What is cost of replacement?

OK - here's the latest. I took the car to the local dealer for final service (way overdue) and told them to check the tires. At turn-in, the dealer was sure to do it anyway. The tires were all within accepted tolerances - so I dodged a $600 bullet.

Wow, you did dodge the bullet. Sometimes our first reactions are the best.

Hi Pd. Thank god it turned out well. What I am surprised at is that with 28k miles on the other tires the dealer still passed the set up as ok. It really makes you wonder about how critical the situation might really be. As others here have mentioned. As you know the whole world is so liability conscious and it forces these statements to CYA. Of coarse without these senarios how would the lawyers survive.
Just a coincidental point of fact. Last week I took my Nissan SUV in for state inspection to the dealer. The mechanic there is a close personal friend and he knows I am a car guy and knowledgable. He immediately noticed that I have one brand of tire on the front and another brand of tire on the back and I assume he is thinking that they were not fitted at the same time. He says to me, 'you got a problem'. He was referring to the possibility of two different tire diameters. I said, 'no I don't, it is 4wd not AWD with positive off switch and I rarely put it into 4wd and especially not on dry surfaces. But that exchange goes to show you what the industry convention is and in my opinion is mostly to cover their butt. So anyway good for you. And you know I do like 3798J's idea to get Tire Rack to shave the one tire. Dave.

We've an outfit here called Olin Mott Tire, they have trued/shaved tires for years. Took many Porsche and BMW cars in to them to have it done. But I think they are only local.