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Which model years will fit a full-size spare tire?

I know that my 1991 (legacy) and 2005 (wrecked by texting driver) fit a full-size spare just right. No modification, no bulging. It just fit.

When did Subaru allow/stop allowing room for a full-size spare in the wheel well?

Part 2: are there realistic ways to modify a 2016 or other Outback to fit a full-size spare? Who has successfully done this?

I live in the West. I like to be far from the pavement. It's criminal (and voids the warranty, and represents untruthful advertising to show Subies off road) to not allow space for a full-size spare. I don't care if there is no spare from the factory, as long as there is space to add your own.

The Subaru manual clearly says that you should not use tires of different diameters - and what do they sell with new vehicles?


Thanks, WV
 

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I just took measurements of my 2018 OB (Gen 5). According to my measurements, a deflated full size spare should fit back there. When I have the time, I will literally take a wheel off to verify.
 

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I would feel comfortable carrying a totally flat full size spare back there. See pics here:

 

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I just took measurements of my 2018 OB (Gen 5). According to my measurements, a deflated full size spare should fit back there. When I have the time, I will literally take a wheel off to verify.
It might be possible to fit a deflated and worn spare in there. Something that is maybe 4/32 tread depth instead of 9?/32.

I've considered cutting the floor pan out and welding in a larger one. There is enough room for a full sized spare between the frame rails.
 

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There is enough room for a full sized spare between the frame rails.
That's a selling point for certain owners - I guess those that go off-road, but even those that are concerned about safety. You'd think they would increase that space in future models to accomodate a real spare. You'd have to get your spare shaved down to be compatible with the other three tires, but it would be a cost saver too, wouldn't it?
 

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It might be possible to fit a deflated and worn spare in there. Something that is maybe 4/32 tread depth instead of 9?/32.

I've considered cutting the floor pan out and welding in a larger one. There is enough room for a full sized spare between the frame rails.
As linked to pics above, I just tried a full size totally flat tire. My tires have about 10k miles on them. The tread is at 9/32” right now. The tire drops in with just a little adjustment that takes about ten seconds. The wheel well cover sits up by about a half inch. There is no way an inflated full size tire would drop in there. Retrofitting the car would be necessary, as you described.
 

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That's a selling point for certain owners - I guess those that go off-road, but even those that are concerned about safety. You'd think they would increase that space in future models to accomodate a real spare. You'd have to get your spare shaved down to be compatible with the other three tires, but it would be a cost saver too, wouldn't it?
Shaving the spare tire would be a constant maintenance thing if you want the full size spare to be exactly the same diameter at all times. I might shave the full size spare once to 7/32”, which is about midway wear. Even though it is a full size spare, I would treat any tire change as temporary because of the different tire wear. But at least the full size spare has a closer diameter and wheel size than the mini spare.
 

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Just as the partial size spare will not be the same effective radius as your tire, you take your full size spare, and put it on. Drive to shop that is capable and have it shaved.

Does that seem practical?
 

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Just as the partial size spare will not be the same effective radius as your tire, you take your full size spare, and put it on. Drive to shop that is capable and have it shaved.

Does that seem practical?
You are talking in generalities on a topic that requires more precision...

1. Difference between mini spare and tires on car = 32/32” diameter at least, plus a width and a weight that are vastly different.

2. Difference between full size spare and tires on car = 8/32” diameter at most, with the same width and the same weight.

Which option do you think will be more problematic for the Outback’s system? If I can get a full size wheel and tire for a bargain, I will be putting a full size spare back there.
 

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Come on. I pegged you as better than that. You are talking in generalities on a topic that requires more precision...
I pegged you as being able to follow me, better than most. :p

Look, I'm advocating putting a full size, brand new spare back there if you can. I was also advocating Subaru make the dimensions bigger so a full size spare can be placed back there, because some customer's would want that.

Now, the thing that is going to affect the AWD system the most in the short term would be effective radius. From the very center of rotation to the maximum extent of the tread. Why? Because circumference is pi*d, where d is diameter, or more commonly 2*pi*r where r is radius.

The circumference of the wheel impacts the rate of rotation to cover the same amount of road surface. If the radius is less than the other wheels, then that wheel must rotate faster, and conversely, if the radius is greater than the other tires, then that tire must rotate slower. For the AWD system, I'm fairly certain, it is the difference in rotational speed that is going to get you.

The sidewall height and width of the tire isn't the critical thing. It's how does the effective radius differ that's important. With certainty, depending on how many miles are on your current set of 4, when you have a critical failure that cannot be plugged of one of your tires, you'd normally put on a partial spare, and you'd take the car to a shop to have another tire of the same size put on. While you are driving with the donut, you most definitely have a different rotational speed between your tires and that of the donut. Yes / no?

You buy one new tire and have it shaved so (providing the tire is of same size and width, sidewall, etc) the tread depths are the same all the way around.

You could purchase 4 new tires, and that's what tire manufacturers and their road hazard warranties really want you to do.

Have I lost you? We may be on the same page, or we may not. Calibrate my thinking.

Recapping: I advocate if the rear wheel well can accommodate it (and maybe Subaru needs to make it larger if the frame supports it), you put a full size rim and spare tire in there that matches the other 4. When one fails, put on the full size spare and go right to a shop and have it shaved down so the tread depth measures approx the same as the other three. Done.
 

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I pegged you as being able to follow me, better than most. :p

Look, I'm advocating putting a full size, brand new spare back there if you can. I was also advocating Subaru make the dimensions bigger so a full size spare can be placed back there, because some customer's would want that.

Now, the thing that is going to affect the AWD system the most in the short term would be effective radius. From the very center of rotation to the maximum extent of the tread. Why? Because circumference is pi*d, where d is diameter, or more commonly 2*pi*r where r is radius.

The circumference of the wheel impacts the rate of rotation to cover the same amount of road surface. If the radius is less than the other wheels, then that wheel must rotate faster, and conversely, if the radius is greater than the other tires, then that tire must rotate slower. For the AWD system, I'm fairly certain, it is the difference in rotational speed that is going to get you.

The sidewall height and width of the tire isn't the critical thing. It's how does the effective radius differ that's important. With certainty, depending on how many miles are on your current set of 4, when you have a critical failure that cannot be plugged of one of your tires, you'd normally put on a partial spare, and you'd take the car to a shop to have another tire of the same size put on. While you are driving with the donut, you most definitely have a different rotational speed between your tires and that of the donut. Yes / no?

You buy one new tire and have it shaved so (providing the tire is of same size and width, sidewall, etc) the tread depths are the same all the way around.

You could purchase 4 new tires, and that's what tire manufacturers and their road hazard warranties really want you to do.

Have I lost you? We may be on the same page, or we may not. Calibrate my thinking.

Recapping: I advocate if the rear wheel well can accommodate it (and maybe Subaru needs to make it larger if the frame supports it), you put a full size rim and spare tire in there that matches the other 4. When one fails, put on the full size spare and go right to a shop and have it shaved down so the tread depth measures approx the same as the other three. Done.
No disagreement here. When you asked above, “Does that seem practical?” it looks like you are using a rhetorical question to say a full size spare is not practical.
 

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Wait instead of welding in a new box to carry the spare what about welding in a flat pan and carrying the spare how trucks do it?

Should be a lot simpler to construct a flat floor.
 

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No disagreement here. When you asked above, “Does that seem practical?” it looks like you are using a rhetorical question to say a full size spare is not practical.
Oh good. I used the wrong phrase. I meant convenient or "practical solution". I've never had a tire shaved before, but if I cannot save a tire, I'm going to replace that tire with a OE tire and have it shaved.

To buy 4 new tires even with a discount for a pro-rated tire that failed (which is all that you'll get, and it has to be another tire by the same manufacturer - it's not a $$ credit - and it may be a hasstle to get them to honor that warranty) is just economic foolishness.

Put another way - you really want to shop for a new set of four, in advance of actually needing them.

Now then, if all the treads were near the wear bars when a tire failed, I would get 4 new tires, and keep that same OE full-size spare.
 

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stfsubaru, Also your plan is a good reason not to pre-shave the full size spare. That way, if you injure one tire on a brand new tire set, you would not have to shave your 3 brand new tires to match your shaved spare. Bottom line, never pre-shave.
 

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Wait instead of welding in a new box to carry the spare what about welding in a flat pan and carrying the spare how trucks do it?

Should be a lot simpler to construct a flat floor.
It might be an option. However, remember, your spare is also part of the rear-end collision safety design. If you have the tire hanging, the effective cushioning might be much less. Don't know.
 

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Wait instead of welding in a new box to carry the spare what about welding in a flat pan and carrying the spare how trucks do it?

Should be a lot simpler to construct a flat floor.
I am not ignoring you. It is just that welding that floor is beyond my skill set!
 

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stfsubaru, Also your plan is a good reason not to pre-shave the full size spare. That way, if you injure one tire on a brand new tire sey, you would not have to shave your 3 brand new tires to match your shaved spare. Bottom line, never pre-shave.
I concurr.
 

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I am not ignoring you. It is just that welding that floor is beyond my skill set!
I can't do much beyond tack welding and bubble gumming. My brothers father was a welder so I always respected the skill but never learned it.

My thought process is: if a hitch spare tire carrier is $500 why not pay a welder instead?

Panel bond is an option as well. Supposedly stronger than welding anyway. Most of the panels are bonded from the factory as best I can tell.
 
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