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Discussion Starter #1
From what I have read mix matching tire sizes and tread patterns can lead to some differential damage so with that being said why did Subaru put a spare tire in the back if using it could lead to some expensive repairs?
 

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Captain James of the SS Impreza has gone down with
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It may be able to get you out of a bad situation. You can't run them for extended periods of time, but to get you out of a jam they come in handy.
 

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as long as the overall diameter of the spare is the same there wouldnt be any issues. plus your not supposed to drive on them long or at fast speeds anyway. width really wouldnt matter. I never looked at my spare but I think it should be the same diameter.
 

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Super Moderator (Actually a SuperSpy)
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Right, the spare is designed to get you back to civilisation.

Once there you're supposed to fix the problem with the full sized wheel and re-fit the full size.

By the way, it's an excellent idea to check the pressure on the spare routinely. I actually inflate mine to the max limit so that even if time passes it'll have enough pressure to get me home.
 

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Discussion Starter #6
Id never drive around on a spare on any car for a long period of time I just thought that I had read of issues of differential problems b/c all the tires were not properly matched and I figured the spare would fall into that category.
 

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The spare is OK to use provided you have also continued using the mains fitted originally with the car. That is, if your original diameter is still present the spare is correct. If you have gone taller/shorter with aftermarket wheels though, the spare will no longer be correct. How incorrect it will be will of course vary.
 

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I was actually wondering the same thing recently. Obviously you don't want to drive far on the spare, but I was wondering just how far you could go on a brand new spare with moderately worn tires on the other corners. I guess it is just important to get into the first tire shop possible, or get the car towed (flatbed of course) if you have AAA and time.
 

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Lando Calrissian
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Agreed.Any spare tire on any car is just for getting you to the nearest repair shop,not to drive around on.
You have obviously never driven through Pittsburgh....here you will see the dinky donut spares on cars for months as if it were an old fashioned fullsize spare.

I am not sure about the spare that came with my rex, but my old CRX had stamped on the spare tire something about under 50mph and 50 mile range.
 

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Super Moderator (Actually a SuperSpy)
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Yes there is a speed limit on the spare. It's also I think in the manual.
 

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That depends on whether you have changed the overall diameter of the wheel + tyre vs. the stock setup.
 

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and the Funky Bunch
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:whoa:
 

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SuperNova
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As a cruel joke.

Given my background and daily interactions, I imagine it being an upper management decision contrary to the expressed opinions of the drive-train engineers. Somewhere there is a Japanese engineer that smirks every time he sees a WRX drive by.

I carry a mini 12 v compressor, fix a flat, and a plug kit. If I can't fix it with that, I'll call a flat bed.
 

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Æternum
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Easy. More differential fires = more money Subaru can charge for repairs!

Alright, enough with the conspiracy theories... the diameter of the stock donut should equal the diameter of the stock wheels. As long as there is no radial mismatch, the differential shouldn't be overworked.
 

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Captain James of the SS Impreza has gone down with
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Easy. More differential fires = more money Subaru can charge for repairs!

Alright, enough with the conspiracy theories... the diameter of the stock donut should equal the diameter of the stock wheels. As long as there is no radial mismatch, the differential shouldn't be overworked.
Well...I ALWAYS call a flatbed. It's a free service included with my insurance payment, so I use it. Like Jeremy, I also carry a small 12v compressor just in case. I don't even carry my spare anymore.

edit: Aren't there stickers you can get that say to only tow with a flatbed? I remember seeing someone have them on their car, I just don't remember where you can get them.
 
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