Sidewall Damage, need your recommedation

[Nachowang]

So thanks to road in the NY/NJ area, one of my tire now has a nice bubble on the sidewall. My question is, can i get away with replacing just one tire and keeping the rest? or should i replace at least 2 so the AWD dont get F'ed up? The tires have approximately 13,000 miles on them. I know Subaru recommends some sort of 2/32nd dimension difference, but i have no idea how to measure that....

[rao]

Any tire shop can measure the tread depth of the tires in about a minute. YOu can also use a penny (Lincoln upside-down and look at the distance to the top of his head or over it). I'd bet that with 13k miles you will be fine, but it is easy enough to know for sure.

[EL PAALO]

I'd bet that with 13k miles you will be fine, but it is easy enough to know for sure.
depends on the tires

[Nachowang]

rao,

Thanks for the quick response! I measured it last night and all treads came out to be by the bridge of lincoln's nose... So I "think" there are plenty of treads left.

[Nachowang]

depends on the tires

Proxes FZ4's

[brett s]

Measure the circumference of the old ones vs the new - if within 1/4" Subaru says you're fine. With tires that wear quickly 13k will be far more than that, with longer wearing tires you may be fine.

1/4" circumference is very little tread depth difference at all unfortunately. Tires are cheaper than a new center diff though!

[direavenger]

FYI, the difference in circumference between my stock RE92's with 18k miles on them and the replacement RE92 that I bought from another member (~5k miles on the replacement) was 3/4".

Save yourself the headache and buy 4 new replacement tires, or buy a replacement from tirerack.com and have them shave the tire down to match the tread depth of your existing tire.

[TravisS]

The Proxes are awfully expensive to replace all 4 after just 13k miles. I'd see if you can get just the 1 replaced and maybe shaved down to match the others. Those tires should only be about 1/4 through their life.

[edit]
Actually, I'm not sure they even sell the FZ4 anymore? Looking around online I don't see anybody with them. 1010tires.com lists them if you search, but not if you actually look at the models they have. Tirerack doesn't list them, and neither does les schwab. Might not have a choice but to replace all 4.
I got tires this morning, they were the Proxes 4 (fairly new model) $680 mounted.

[one69chev]

if you have any question concerning the possible damage to the car because of tread depth, buy a pair and then use the other old tire---without the bubble---for a spare.

[brett s]

That won't save your center diff if there's too much difference between circumference on each set of two.

[sebberry]

Hmm... when I wrecked one of my tires, they replaced just one... said they worked on Subaru's all the time. (tire shop, not the dealer) There was about half the tread missing from the old tire, but they said it would be alright..

I had them put it on the front as there would be less of a difference in rotations, but then my dealer just rotated them as part of the 72,000km service and put the newer tire on the back with the half worn one on the limited slip... :(

[Nachowang]

The Proxes are awfully expensive to replace all 4 after just 13k miles. I'd see if you can get just the 1 replaced and maybe shaved down to match the others. Those tires should only be about 1/4 through their life.

[edit]
Actually, I'm not sure they even sell the FZ4 anymore? Looking around online I don't see anybody with them. 1010tires.com lists them if you search, but not if you actually look at the models they have. Tirerack doesn't list them, and neither does les schwab. Might not have a choice but to replace all 4.
I got tires this morning, they were the Proxes 4 (fairly new model) $680 mounted.

I heard they will be discontinued, but the tire place i called today can still get em straight from Toyo.

[Nachowang]

Hmm... when I wrecked one of my tires, they replaced just one... said they worked on Subaru's all the time. (tire shop, not the dealer) There was about half the tread missing from the old tire, but they said it would be alright..

I had them put it on the front as there would be less of a difference in rotations, but then my dealer just rotated them as part of the 72,000km service and put the newer tire on the back with the half worn one on the limited slip... :(

Did you feel any unbalance or vibrations at all? The tire shop mentioned the same thing to me.

[one69chev]

That won't save your center diff if there's too much difference between circumference on each set of two.

so your saying that a set of new in front and a set of 13k in rear will damage a diff? doesn't sound like the diff's built very well then, esp when we're talking about thousands of an inch. if that's all it takes to blow a subie diff, i guess i shoulda bought a different car......:eek:

[sebberry]

so your saying that a set of new in front and a set of 13k in rear will damage a diff? doesn't sound like the diff's built very well then, esp when we're talking about thousands of an inch. if that's all it takes to blow a subie diff, i guess i shoulda bought a different car......:eek:

Well, considering that the diffs work to lock the front and rear wheels together (MT) as soon as slippage occurs, if the front wheels are making more turns than the rear wheels over the same distance, then the center diff will be working to limit the difference between the two.

[sebberry]

Did you feel any unbalance or vibrations at all? The tire shop mentioned the same thing to me.

I don't think so...

[TravisS]

It's not a Subaru exclusive issue, other AWD vehicles require matching tire diameters as well.
But ultimately it comes down to the viscous diff (I think). Basically the different sized tires are enough to be seen as "slip", and driving like this long enough will cause bad things to happen.

[one69chev]

my main point is overall durability. SOA did not design and manufacture a diff that would implode simply because of 2/32's tread wear difference. most new performance tires new have 10/32's tread, so running a pair w/ appro 8/32's with a new pair is not going to do any damage. i've sold plenty of tires, and the things i always looked for was tires of the same speed rating, load, ply rating and r.p.m---revolutions per mile.

these factors in my experience are more important that ditching 3 practically new tires because the fourth took a crap. now, if the others were worn significantly, the traction difference alone would make the decision a no-brainer.

but hey, if your wallet can stand it, throw on a new set and save the others......

[brett s]

Ask an experienced Subaru mechanic how many center diff's they've changed because someone didn't follow the guidelines on circumference differences - they really won't tolerate huge differences long term & will fail.

That doesn't mean it'll for sure be a problem if you're just over that 1/4" limit, but I'd want to know exactly how close I was to that. If your old tires are say 50-60% tread, you're *way* past 1/4" difference...do the math.

Do what you like with your car, I'll keep them close - if that means buying 4 tires or getting a new one shaved if I have a bit of bad luck, so be it. Unless I'm trading it soon or something maybe :)

[pillboy]

How can a car enthusiast not have one of these?

[Nachowang]

Well, got the new tires today and took the measurement. It falls well below the 1/4" circumference limit....phew!