[timler63]

I have a 2015 Outback 25i. I recently blew a tire hitting a pothole. I took it to Discount Tire to get it fixed. I found out that it could not be fixed and worse that due to the symmetrical AWD I would need to replace all 4 tires or risk wrecking the transfer case. Has anyone else encountered this situation? Both Subaru service and a mechanic whom I trust confirmed this is actually the case.

 

[Brucey]

This is correct assuming they aren't brand new tires.

If the tires diameter is off by more than a small amount the AWD system won't know what to do.

Your only option besides replacing all 4 is buying an identical tire and shaving it down.

 

[KansasMatthew]

^^^

That's the deal. It's not just a Subaru thing, either.

 

[AWDFTW]

Oh it's this thread again.

 

[subiesailor]

ANY FULL TIME AWD must have all 4 tires near identical.

 

[Wilko1]

If your tyres (Aussie spelling) are near the end of their life buy four new ones. If they are still good get one identical tyre and have it shaved to the correct size like Brucey has suggested above. Any tyre shop worth its weight would suggest this. A bad shop will tell you to replace all four.

 

[martin_j001]

This is correct assuming they aren't brand new tires.

If the tires diameter is off by more than a small amount the AWD system won't know what to do.

Your only option besides replacing all 4 is buying an identical tire and shaving it down.

For those of us that are newer here, what is a "small amount"? Is there a guideline as far as that goes?

 

[z28dug]

For those of us that are newer here, what is a "small amount"? Is there a guideline as far as that goes?

It's in the manual. As I recall the allowable tread difference between tires is 2/32 of an inch. Not very much.

 

[martin_j001]

It's in the manual. As I recall the allowable tread difference between tires is 2/32 of an inch. Not very much.

Good to know, I'll look it up. I looked for info about spare size, but must not have paid attention to this if I encountered it...I'll check again.

 

[eagleeye]

as a alternative to buying 4:

a big tire store like discount tire. can shave a new one down to match what you got.

or maybe you can locate a used one to match what you got. (hard for time though....like you would be walking around a pick and pull with a tire gauge,...looking for exactly the tires you have....vs. just going on with your life).

_____

but if the OP is driving on the crappy original set for 3-4 years,
....maybe they are getting low on tread depth, and therefore past being worth dealing with.

and its time to move on to something safer in rain / snow.

____

and the tire discussion / tread depth between the tires is hopefully right in the owners manual....just like discussion of putting the doughnut spare only on the back so as to not inhibit steering and braking so much.

 

[NVdesertrat]

I recentley bought all 4. Since then I have noticed that the Hispanic tire stores sell used tires of varying tread wear. I am sure one has my 3 good tires for resale I will definitley check that out next time i have tire trouble.

I don't see how the dinky factory spare will work. In Nevada it is often 100 miles between service stations. Even in Utah it was 100 mles accross the Wendover Salt Flsts.

I am looking for a extra coke bittle wheel and will throw a full size spare on the roof. I know from experience the small diameter donut spares may not work on back country roads as they provide insufficient clearance. They especially cause the back end to drag in dips and washes.

 

[deuces]

Tire Rack can send a tire shaved to match your other 3, if you can wait for shipping. Contingent on them selling the same model tire you have of course. I had them do this for me once a few years ago. Thought it was $15 but just looked at their website and it looks like $25-35 now.

 

[skipw]

I don't see how the dinky factory spare will work. In Nevada it is often 100 miles between service stations. Even in Utah it was 100 mles accross the Wendover Salt Flsts.

If stations are 100 miles apart, you're no more than 50 miles from one. Keep your speed down (way down) and you should be OK. If you do have to drive longer distance on the donut, drive even more slowly to keep heat build-up in the diff and transfer case down.

I am looking for a extra coke bittle wheel and will throw a full size spare on the roof. I know from experience the small diameter donut spares may not work on back country roads as they provide insufficient clearance. They especially cause the back end to drag in dips and washes.

That is a concern. I think a lot of folks keep a patch kit and air pump with them for this reason. Also, I think a full-size spare will fit in the well if it's not inflated, so that and an air pump may be an option.

 

[DugsSin]

I would check that the rim isn't bent too.

 

[dukey33]

The "dinky" spare in the OB is only 1/2" shorter than the standard tire. It is not a tiny space saver like in an economy car. There is enough height difference to be a problem to the AWD system in prolonged use and high speed use . It also may have trouble surviving out on the trail. But let's not paint the spare as some 13" diameter donut,

 

[NVdesertrat]

I hope a full sized spare will fit. Easy to carry can of air. We once had a flat 50 miles from pavement in a S10 pickup. Rear bumper drug ground with donat spare. We had to put it on front. Ended up plugging flat to make it out. If tire tread is so very sensative- a donaut spare is ridiculus and makes no sense..

 

[skipw]

The "dinky" spare in the OB is only 1/2" shorter than the standard tire. It is not a tiny space saver like in an economy car. There is enough height difference to be a problem to the AWD system in prolonged use and high speed use . It also may have trouble surviving out on the trail. But let's not paint the spare as some 13" diameter donut,

You're right! :surprise: [ ]

From https://tiresize.com/comparison/

Tire Size Comparison Calculator
Size 1 225 / 55 R 17
Size 2 155 / 70 R 17

Size 1 : Size 2
Diameter 26.7" : 25.5", -4.5%
Width 8.9" : 6.1", -31.5%
Sidewall 4.9" : 4.3", -12.2%
Circum. 84" : 80.2", -4.5%
Revs/Mile 754 : 790, +36

They differ in diameter by 1.2", so the difference in radius, which affects ground clearance, is 0.6". Since the spare is much higher pressure it might not squat as much, so 0.5" is probably a good estimate. That's less than I thought.

 

[skipw]

I hope a full sized spare will fit. Easy to carry can of air. We once had a flat 50 miles from pavement in a S10 pickup. Rear bumper drug ground with donat spare. We had to put it on front. Ended up plugging flat to make it out.

Maybe that spare tire was much smaller than these are. Dunno.

I think most people doing 50-mile rugged off-road trips in Outbacks bring a full-size spare, or prepare to deal with it in other ways, as it sounds like y'all did.

If tire tread is so very sensative- a donaut spare is ridiculus and makes no sense..

It makes perfect sense in an emergency under most circumstances. Just swap it out as soon as you can and keep your speed down until then. The space-saver allows for a bigger fuel tank and weighs less. I appreciate the generous 18.5 gallon fuel tank all the time. I may *never* have to use the spare tire at all, but they are likely perfectly adequate 99.44% of the times they are called upon. If you're going to be hundreds of miles from pavement on rough roads, it probably *won't* be adequate, but how many people do that? Probably the worst that most of these cars face is road construction on the way to the kids' soccer practice after a heavy rain.