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Forester
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19 Posts
Discussion Starter #1
I remember reading on the forums somewhere that if one tire blows out, you'd have to replace all the tires, or have the one shaved.

The reason, if i remember right, was that if one tire was slightly smaller/larger it would put strain on the AWD system.

Could anyone divulge more information on this?


I recently was in a car accident and the repair man hadnt heard of this when I mentioned it. He is going to call subaru to confirm this information and I hope subaru will agree so that insurance will cover all four tires.
 

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Premium Member
2019 Crosstrek 2018 XT
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14,399 Posts
This has been often discussed but I believe that the official Subaru stance is still no more than 1/4 inch difference at the rolling circumference.
 

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2017 Forester XT Touring
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1,067 Posts
Try searching, it will bring up a lot of results such as:

Tire Replacement After Flat

Did I need to replace all 4 tires

Need one new tire up front

...and many more. The short answer is, the tires need to be within 1/4 of an inch circumference of one another. So if they are worn too far, a new tire will be too large to meet that criteria. Your options at that point are to either A) get 4 new tires, or B) have a new tire mounted, find a wheel/tire/performance shop that you can take the wheel/tire to and have them shave it down to match your other ones... this is what I did.
 

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2018 2.5i Premium CVT
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18,971 Posts
The answer to this and many other common problems can be found in this sticky thread in the New Member Introductions Forum, or in the threads that it links to.
 

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Forester
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19 Posts
Discussion Starter #6
Subaru once specified a maximum difference in rolling circumference of 1/4" (which is pretty tiny when translated into difference in tread depth—divide by 2 Pi!), though they have since backed off from that specific figure.
Any info on what the new figure is?
 

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2018 2.5i Premium CVT
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18,971 Posts
They don't appear to have an opinion other than reasonable and prudent. If they did, they wouldn't be able to use the donut spare!

Many of us have cheated a bit and lived to tell about it. But nobody knows for sure where the cutoff point might lie.
 

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Forester
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19 Posts
Discussion Starter #10
Well shucks, if subaru doesnt come through with the info, looks like ill be buying the a new set of tires myself :(

I vote subaru makes a forester model with a full-size rear mount tire!
 

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2018 2.5i Premium CVT
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18,971 Posts
They had full size spares up into the mid-2000s. There's plenty of room in there for it.
 

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Forester
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Discussion Starter #12
plenty of room, yeah, but if its rear-mounted it makes it look rugged and utilitarian. :)
 

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2009 Forester Limited Manual
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117 Posts
They had full size spares up into the mid-2000s. There's plenty of room in there for it.
Yup, here's a thread showing full sized spares. Lots of pictures regrading an '09.

As discussed in other threads, you can get a new/used full size tire, mounted on a black steel rim, shave it , etc. Or pay extra get a matching tire and rim then include as part of a 5 tire-rotation. The 5 tire rotation will hopefully ensure the spare is within the same diameter as the other 4.

I do the 5-tire rotation [Pattern G], but suspect I'll need to one day buy a set of 5 tires instead of 4..... at least I should get more miles out of 5 tires than 4... :shrug:

Cheers,
G
 

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2007 XT Sport 5MT
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24,015 Posts
if you check the tire compared to the originals... if they're within 3/16 of tread wear, you're alright.

that is strictly based on whether or not you attempt to replace it with the exact same size and model tire.
 

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2005 Impreza RS Wagon Auto
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3,658 Posts
They don't appear to have an opinion other than reasonable and prudent. If they did, they wouldn't be able to use the donut spare!

Many of us have cheated a bit and lived to tell about it. But nobody knows for sure where the cutoff point might lie.
I run two different brand sets of two on two Subys, nothing has exploded yet lol...
 
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