[andiamo]

Hello,

I'm well-aware of the limitations of the donut, and have been interested in upgrading to a full-sized spare for some time.

I'm currently running the stock Yokahama Geolanders (225/55R17), and am looking to upgrade to something a little quieter, probably the Michelin Primacy MXV4's in the same size.

Can I get away with buying a 17'' steel rim and using one of my old Geolanders as the full-sized spare? So this would be a full-sized spare of the same size as the new Michelins, but probably of different tread wear.

I know Subaru is really touchy about any differences in tires messing up the AWD, so I wanted to get a little corroboration of the idea.

Thanks!

P.S. 2011 2.5X Limited

 

[Y.B]

The 2011's have what I was told is a "full height" spare "donut" so the car does not dip to the road like the old original ones did. Never had to use it yet.
Oh, and I dumped my Geolanders as well, crappy tire. I went with a Goodyear tire and the improvement was immediately noticed.

From what I have learned about AWD, it would be wiser to buy 5 tires and add the spare to the tire rotation sequence. Having a tire with less tread may cause damage if left on over a long period of time. Maybe a short couple of miles may not hurt.

 

[adc]

Just use it. It will be fine for use as a spare. If you are going to drive in the range of a couple hundred miles install the AWD fuse in the front fuse compartment. Actually install it once so you know how to do it.

5 identical tires gets expensive rotating into the origional 4 wheels and with that there is increased chance of damaging a TPS unit.

 

[Y.B]

That may be fine for most situations on long hauls. However depending on ones location and driving conditions, some instances you may need the AWD so disabling it may not be the best option.

Life has taught me that on the road it is better to err on the side of caution.

 

[trailangel]

The 2011's have what I was told is a "full height" spare "donut"

So.. where did you get this information?

 

[adc]

However depending on ones location and driving conditions, some instances you may need the AWD so disabling it may not be the best option.

Not to belabor this but in a snow condition disabling won't be necessary bc tires will slip and there won't be any strain of the diff. But yea..being prepared and erring on the side of caution ftw. I have learned this lesson also.

 

[Y.B]

So.. where did you get this information?

The dealer when I bought the car. I inquired if it had a full size spare like my '02 did.

 

[Y.B]

Not to belabor this but in a snow condition disabliong won't be necessary bc tires will slipv and there won't be any strain of the diff.

I am by no means an AWD expert. I can only relay what I have been told by others who know or have read....

I had one tire go flat with the Geolandars and was told the projectiles were to close to the sidewall and needed a new tire. Thus I would have more tread on one tire than the others. I did some inquiring and found that it is recommended to keep all tires as close as possible (this info did not come from the tire store)

 

[campisi]

Just use it. It will be fine for use as a spare. If you are going to drive in the range of a couple hundred miles install the AWD fuse in the front fuse compartment. Actually install it once so you know how to do it.

5 identical tires gets expensive rotating into the origional 4 wheels and with that there is increased chance of damaging a TPS unit.

Agree with this.

 

[trailangel]

The dealer when I bought the car. I inquired if it had a full size spare like my '02 did.

What size is the donut spare that came with your car?

 

[wr moore]

The spare in my '14 is darn close in OD to the OEM tire. It may not be as wide, but it isn't the wheelbarrow wheel sometimes seen in other makes. The spare tire well is large enough for a full size, but you lose the styrofoam storage tray.

BTW, one of the other cars I looked at didn't even come with a spare. You got 3 cans of fix-a-flat of some type instead.

To the OP: a near bald used tire combined with 3 nearly new tires would probably be worse than using the factory spare. Also, just because two different brand/line tires have the same XXX/YYR17 numbers doesn't mean they'll have the same rolling diameter, which is the number that matters. Note that the factory spare is to be used on a rear wheel only!

 

[trailangel]

I'd like to know the size of the tire. If it's larger than previous pony tires I want one.

 

[Y.B]

Here is the tire. Sorry for the poor quality, it is dark and cold out there.
The tire size reads T155-70D17

 

[andiamo]

Thanks for the feedback, all.

To the poster who pointed out rolling diameter - the Michelins run 778 revs per mile, while the Geolanders run 775. So close, but no cigar. Maybe close enough, but I'd definitely disable the AWD before proceeding.

As for tire wear, I'm betting that the donut (being new and unable to be put into the tire rotation) is probably pretty different from the other 3 tires whenever it's put on.

 

[Y.B]

Ok, the manual states:

paraphrased: All tires must be of the same brand, construction, degree of wear load index, size. Mixing of different types, sizes or degree of wear can result in damage to the power train. It can also dangerously reduce controllability (sic) and braking that could lead to an accident.

As for the spare:

Never use any temporary spare tire other than the original due to damage to the power train. Do not exceed 50 mph and only use for emergency's. Remove as soon as possible.

Also states about installing the Fuse in the FWD slot to disable the AWD

 

[adc]

the Michelins run 778 revs per mile, while the Geolanders run 775. So close, but no cigar.

That works out to a difference of about .31" vs .25" allowed. = good enough in my book.

 

[campisi]

Thanks for the feedback, all.

To the poster who pointed out rolling diameter - the Michelins run 778 revs per mile, while the Geolanders run 775. So close, but no cigar. Maybe close enough, but I'd definitely disable the AWD before proceeding.

As for tire wear, I'm betting that the donut (being new and unable to be put into the tire rotation) is probably pretty different from the other 3 tires whenever it's put on.

That bet would pay off. The 2011 has 155/70/17 spare which is 25.54" tall (nominally) while the OEM 225/55/17 is 26.74" tall (nominally) and the OTHER OEM tire size is 215/65/16 is 27.0" tall. Now, as your tires wear the diameter will decrease getting the OEM's closer to the diameter of the donut.
This tells me that Subaru doesn't believe that an inch or more difference in tire diameter won't destroy or damage the drivetrain IF USED IN THE WAY SUBARU DESCRIBES IN THE MANUAL.

Personally, I would have no problem whatsoever putting a full-size spare on my vehicle that was an inch different than the others but I'd only use it for whatever distance I had to get the main tire repaired or replaced. I also have a manual transmission so I don't have to worry about the AWD fuse issue.

 

[Inspector]

I asked the same question(because I have the exact same situation) http://www.subaruforester.org/vbulletin/f72/full-size-spare-awd-fuse-230346/

and also received a mixed response. Some people think you have to pull the fuse, others say it wont do anything,

 

[adc]

I
and also received a mixed response. Some people think you have to pull the fuse, others say it wont do anything,

Actually you "install" the fuse and it disconnects the front from the rear which "will" do something.

 

[crewzer]

paraphrased: All tires must be of the same brand, construction, degree of wear load index, size. Mixing of different types, sizes or degree of wear can result in damage to the power train. It can also dangerously reduce controllability (sic) and braking that could lead to an accident.

I find this OM statement to be well-intended guidance, but taken as an absolute, it's nonsense, IMHO. Specifically, if true, then why is it OK to use the temp spare which is not the same brand, not the same load index, and not the same size as the OEM road tires?

I'd much rather use a full-size spare that's close to the OEM tire size in place of the temp spare.

the Michelins run 778 revs per mile, while the Geolanders run 775.

The revs per mile count will increase as the tires wear. 775 is more than close enough for the 772, especially for a single spare tire use, where the axle differential will reduce the effect of the tire size difference on the drive shafts by one-half.

HTH,
Jim / crewzer