[darkbyrd]

I had a flat tire on my 2k outback ltd, and drove on it long enough to ruin the sidewall. The tire needs to be replaced, but there is still enough life left in the other three to keep going for awhile longer. Will I be okay putting a used tire on the wheel, with about as much tread as the others, until it is time to replace all four?

Also, the inside rim of the wheel (OEM Al wheels) is slightly bent. Looks more like a flat spot than a bend. Do I need to replace the wheel, or at least have someone knowledgeable look at it before having another tire mounted?

TIA

 

[SE95]

You can potentially get away with a used tire if it is identical to the other three. Same make, model, tread depth and pattern. I would get the wheel checked out by a shop.

 

[rasterman]

You might want to check your owners' manual. Subarus are very sensitive to differences in tread height, but the spec is a little different from one model/year to the next.

As a general rule, if you bought the other 3 tires in the last year I'd say you're probably ok. Otherwise, it's time to get a new set.

Regarding the rim, best to get somebody to look at it, maybe measure the runout. It might just look funny, but it could also have a more serious problem.

 

[darkbyrd]

Thanks for the quick advice. In years past, I had a source for free used tires from my FIL, so I have matching tires on the front (one is ruined now) and mismatched tires on the back (but all the same size, 205/60 I think). Is matching the tire (brand and tread) that critical, or will I be okay for the next six months when I plan on replacing all 4 tires with new, and probably back to factory specs.

 

[SE95]

You likely have already caused irreversible damage to your drive train. The downside of Subarus excellent AWD system is that it is very sensitive to minute differences. All four tires must be identical at all times. I would not be surprised if you have transmission or differential problems in the not too distant future

 

[SE95]

Also your Outback should have 225/60R16s on it.

 

[rasterman]

I'll put it this way- only race cars are pickier about matching tires.

Mismatched tires on a Subaru is a great way to do 200,000 miles worth of wear on the AWD system in 50,000 miles or less.

 

[darkbyrd]

You likely have already caused irreversible damage to your drive train. The downside of Subarus excellent AWD system is that it is very sensitive to minute differences. All four tires must be identical at all times. I would not be surprised if you have transmission or differential problems in the not too distant future

Yeah, that is pretty much what I figured out when I first came looking on here. Live and learn I guess. I had the transmission rebuilt 30k miles ago, at 150k, and things have been going well since. What symptoms of drive train damage do I need to be particularly aware of going forward? Anything I can do to prevent problems from getting worse and more expensive at this point?

 

[rasterman]

Search this board for the phrase "torque bind."

That is the term applied to a group of AWD-related problems.

The best thing you can do is to accelerate your schedule for 4-tire replacement.

I suppose it is worth pointing out that wear from mismatched tires only occurs when you have good traction. So on the off chance that you've been driving entirely in soft sand, mud or ice, you're good to go as-is.

Also, a few folks were tossing around some theory in another thread. The idea is that by matching pairs on opposite sides of the car, you might equalize the stress. It's probably a terrible idea for handling, especially emergency maneuvering, but it would likely take the strain off the transmission.

 

[idosubaru]

Is matching the tire (brand and tread) that critical.

no, not at all, it is done *all the time*, extremely common. the internet is ripe with black and white apocalyptic talk of tires though so you'll have to wade carefully to find the best fit for you. i'll try to help since i know how common this is and what and why you have options.

Replacing all 4 is wise advice for the masses who don't have time to focus on options, details, keeping track of maintenance, etc - and i am this way in other venues because i don't have time - it is a very wise one-size-fits-all anecdote to be sure. But there are other approaches that are fine and they are common place and offer an excellent fit for certain people.They won't be known by those that have never tried, seen, or done it once...much less hundreds of times, so you'll expect all of those folks to not buy into this at all since "suspicion often creates what it suspects".

i'm not recommending, nor have I ever done this, but it's just an example of how technically deprived many tire responses are. They aren't driven by technical aspects, they are driven by literature printed by Subaru - which is good advice as I've already said, but nonetheless some folks have the capacity to look beyond just what Mother Subaru says:
One *can* (be careful to do it right) install two new tires on one front and one rear opposite side tires because of the way the front, center and rear differentials work. This is done all the time by tire shops in Subaru rich areas that know this. Unless shops are well informing their customers or they are coming back for all future rotations though I think that's risky for a shop to do.

If you've even seen a Subaru stuck in the mud, snow, high centered, etc - you will notice that one front tire spins and the opposite side rear tire spins - the reason for this is closely linked to the previous paragraph about differentials.

Again - im' not suggesting this - i'm just suggesting that the one-size-fits all anecdotes that are blindly followed without experience are not practically well informed about how differentials work, why this tire stipulation is in place, and what is actually happening and what is actually possible.

There are options for folks who want to learn. Which is probably only a few percent of people...which brings us back to one-size-fits-all approaches being a very good idea....so tread carefully I agree. Follow the advice of someone that knows what they're talking about and don't sell or give the car to someone with wonky tires.

will I be okay for the next six months when I plan on replacing all 4 tires with new, and probably back to factory specs.

you will be fine indefinitely so long as the tires are matching in size (tire size and tread depth) and you rotate them properly.

this is not a big deal. you'd get a much broader and more technical advice on this question at USMB.

 

[idosubaru]

as to the wheel - is it just the lip that looks bent or the actual rim itself?
curb rash and damage to the lip isn't a big deal...depending of course...
a picture might help.

 

[darkbyrd]

I'll be reading up on torque bind this evening. In the meantime, I think my plan needs to be to replace the ruined tire with an equally wore-out one, and plan to put a new set on when I get my money back from Uncle Sam. I do a lot of off-pavement driving on forest roads, but also need to be able to count on it in winter weather.

Here's a picture of the wheel. It looks like it is just the lip that is bent. When I aired up the tire after I had it off, it did not leak from this area.

 

[idosubaru]

i have little experience with wheels but the lips often get damaged/bent so that shouldn't matter too much on it's own, if nothing else got tweaked.

if it's holding air i'd be tempted to run it, have them balance it, and see if it has any symptoms.