Using a Temporary Spare Tire on an AWD Vehicle

I own a 2009 Subaru Forester, and I am very impressed with its traction - invaluable during our North Dakota winters. However, the owner’s manual advises to ONLY use the temporary spare on the rear wheels, and only after making the vehicle FWD vice AWD by inserting a spare fuse into a certain spot. The temporary spare must NEVER be placed on the front wheels, otherwise serious damage may result to the drivetrain. I find this ridiculous! I would rather sacrifice a little room in order to have a full-sized spare, than have to put the temp spare on a rear wheel, and move the rear wheel to the front (if I have a flat in the front).

Question: Do you know of any other AWD vehicles with this restriction? I realize that others are really FWD or RWD until slippage, then power is sent to other wheels - while Subaru is AWD all of the time (viscuous connection).

You say "I realize . . . "

That’s the reason for the restriction. Subaru’s AWD system is full time, not part time like most of the others, and does not tolerate large differences in wheel/tire diameter, such as when you need to use the temporary spare tire.

If you’re that worried about a flat, buy a full size spare and carry it in the rear cargo area. Otherwise, I suggest you follow the instructions in the owner’s manual if you wish to avoid expensive damage to the AWD system.

It’s not ridiculous. It’s necessary to protect the AWD system. If you don’t like this minor limitation, perhaps a Subaru is not for you.

A full size spare won’t get any wear. The other four will. Unless you rotate all five regularly, the spare will fairly soon be greater in circumference than the others. That will cause one axle to turn at an unacceptably different RPM than it’s opposite. The temp spare is a different size, too. That’s why they’re telling you this.

The reason Subaru gives this warning is to guard against unneccessary wear on very expensive drive train components. The wear can result from the drive train trying to accomodate a more or less constant difference in axle RPM, rather than that caused by just occasionally turning a corner. Subaru’s AWD system is about as good as it gets for the price. This isn’t a big deal.

I want to congratulate you for reading the manual BEFORE making the mistake and ruining the car. Now if I were you I will just follow whatever the manual says.

On some models, you get NO SPARE! You get expensive “run-flat” tires that last about half as long as quality “normal” tires…

Yes - it would be foolish not to do so.

Caddyman is right about no spare. My oldest son has a Dodge Caliber R/T and it has a space saver spare but I think the SRT versions do not even come with a spare tire.

One of my biggest complaints other than the T-type spares are the lousy jacks that come with new cars. It can be tough enough to raise one wheel in broad daylight much less doing it in the dark; especially on a dirt or grass shoulder as is common around here.

I know it would crimp the style of the car designers but I’d like to see cars fitted with a plug on the side like the old VW Beetles. A guy could stab that jack in the hole, raise both wheels on one side or the other at the same time, and the car would not fall off of that jack. This was easy to do even at night with little or no lighting.

You should have seen me one night about 9 o’clock after running over a chunk of sharpened scrap metal on a lonely highway about 8 miles from my home. The metal not only took out the tire, it also took out the airbag on the LF of my previous Lincoln Mark.
This left me in the dark with a collapsed front suspension and no way was that jack in the trunk going underneath the car as it was slammed to the ground with less than 2" of clearance.
Walking, hitchhiking, and about 3 trips back out there with various tools and jacks later… :frowning:

Thanks for your response.
You might think it’s a “big deal” if you had to change two tires instead of one while it’s minus 20 - 30F. A vehicle this size - with this drive system - could have and should have been designed to accommodate a full sized spare. A friend’s '99 VW Passat came with a full sized spare, very neatly stowed away inside and it still has a very generous trunk - surely, Subaru could have done likewise. I think it’s a very good vehicle with outstanding winter traction - but this is a notablel shortcoming, in my opinion. What do you think it would do to the sales figures, if people were aware of this? I think most people aren’t (the owner’s manual is sealed, when new).

Unfortunately like 03impreza pointed out, even a full size spare wouldn’t solve your problem since it wouldn’t have worn to the same size as the other tires unless you were doing rotations with all 5 tires (which not all owners would do). In the end the only way Subaru could have avoided this problem would be to not have the full time AWD, which is the major selling point of their cars.

If you don’t want to change two tires when it’s minus 20-30F then I simply suggest you purchase AAA or some comparable service and have them change the tires for you.

A Subaru CANNOT run a mismatched tire for very long without causing damage to the AWD. It is an engineering compromise that Subaru has for a very simple/reliable AWD system that is about 20 years in design but superior to anything introduced since except Audi.

Even with a full size spare the tire would be mismatched and still cause the same stress to drivetrain.

Audi has this restriction also of running closely matched tires in rolling circumference(distance around tire that touches road).


As nfs480 pointed out, 03impreza was correct about a full-size spare not being a real solution to this issue. The problem for the AWD system is one of tires that are not sized identically, and an un-worn, pristine full-size spare will be larger in circumference than the 4 other tires on the car after 10k miles or so, and the difference will grow as the “road tires” continue to wear.

The only way that a full-size spare would be a solution would be if you faithfully included it in your 7,500 mile tire rotations. Most people with full-size spares rarely do this.

The main reason for the ubiquity of tiny “donut” spares is the weight-saving that results in slightly better gas mileage–an issue near and dear to both automakers and consumers. And, of course, the size of a vehicle and its ability to accomodate a full-size spare also has something to do with the issue.

You can resolve this issue yourself by carrying a full-size spare in your cargo area, but that presents two problems:

You will be giving up much, if not most, of your cargo room.
An unsecured tire can be hazardous in the event of a collision.

Thanks for your response.

LOL ! Call AAA ? Good one.

Yes - I realize the bit about the diameter etc., but I believe a better solution would have been to design the vehicle so that it would neatly stow a full sized spare, and include strategically placed warning stickers which stress the necessity of a five-tire rotation regimen (if that is indeed a solution). That Subaru would manufacuture such a very fine vehicle, and then equip it with a spare which - (and I stress this:) if used in the way that most people probably assume it is to be used, may cause serious damage - is surprising and dissappointing to me. Yes - not all owners would faithfully do the five tire rotation, but with use of the cautionary/advisory stickers - probably more than are aware (as a result of actually reading their owner’s manual) of the danger of serious damage involved in using their current spare. A kind of “flash survey” of owners, may produce interesting results.

In most other regards, I’m very pleased with this vehicle - and I realize that it’s not the worst case out there, as far as spare tires. Run-flat tires are expensive and don’t last, and some other vehicles stow their tires in hard-to-get-at place (even under the second row seat, underneath in a minivan). But I was not pleased to learn of this, only after reading my manual (sealed when new) - and I did my research.

I take it that the spare tire issue is your only gripe with this car?
Or is is the final straw with all the other things that you dislike about the car, and the winter snow traction is its only saving grace in your opinion?

First of all, the chances of getting a flat on a new car is pretty low, unless you live in an area that has a lot of construction where they are building houses, or replacing roofs, and nails are falling off of trucks by the bucket load.

Then, you would actually have to have the flat on the front tire of your car, for the two tire switch requirement to actually be an issue.

And to top it off, you would have to have this flat occur when you are driving in bad weather, to put the cherry on top of the whipped cream.

So, unless this has actually already happened to you, why don’t you just spend your time and energy on something more worthwhile. Like buying a membership to AAA, or a road hazard policy for your tires at Discount Tire, or something similar, so that if this should ever happen, you can have someone else resolve the issue for you, and you don’t have to worry about flat tires, changing tires, or rotating tires.

And no, this would NOT affect Subaru’s sales figures one iota if the public knew about it on a mass scale. Do you want to know why?

Because people who buy Subaru’s only care about one thing when they go into a Subaru dealership looking to buy a car:

They want an ALL WHEEL DRIVE CAR that works well in the snow, and has a perceived notion of reliability. They sell Subaru’s here in Colorado by the truck load come the fall and winter. Some of the worst drivers I’ve ever seen in my life occupy the roads here, and are all too frequently behind the wheel of a Subaru Outback.


You don’t seem to know about FWD tire changes, then. Putting the donut on the drive wheels can damage your car as well. Those of us with FWD cars have to change it twice if a front tire goes flat too, unless we have a full sized spare.

In other words, having to do extra work to change a tire is hardly the sole domain of Subaru.

Thanks for your response.

So - you’re telling me that owner’s manuals of all FWD cars say never to put the donut on the front? I don’t think so.

Sure - use of the donut must be on a very temporary basis, regardless of where it’s put - but “color me skeptical” regarding your statement “those of us with FWD have to change it twice if a front tire goes flat too.”

My 1989 Accord tells me to keep the smaller diameter tire away from the front to avoid damage to the differential within the transmission, this is a very true fact about FWD cars. If one axle is turning at a different rate than the other because the tires are different sizes damage to the transmission is likely to result.

" I find this ridiculous! "

I agree with you. Although these vehicles provide better traction, the problems with spare tires, matched tires, driveline problems, etcetera, make them a poor choice for most of the motoring public.

Subarus has a smaller market share than what is reflected in the enormous number of owner / operator problems and complaints seen on this site and others. It is disproportional to say the least.

I always take vehicles on extended test drives (at least overnight and usually longer), before deciding on purchasing one. I take time to beccome familiar with the cars’ features that are outlined in the Owner’s Manual.

I’d say that it’s a good thing that you eventually looked in the manual. Many owners of these cars apparently never do. Always carry a cell phone and just plan on a flatbed tow if you have a flat. Fortunately flat tires don’t happen very often.

These cars are not for everybody. If you’re willing to put up with the idiosyncrasies, some of which are more expensive and inconvenient than with a FWD, as a trade-off for improved traction, then you are one of the folks that would want one.

We live in an area that receives plenty of extreme weather (ice, blizzards, wind, extrerme cold) and we’ve never needed anything other than FWD. We live 20 miles, one way, from town and school and 50 miles from work and travel rural roads. Our problem is usually visibility that makes driving dangerous before traction is an issue. When the weather gets really bad, schools and businesses close and / or the State Police require everybody off the roads.

I think a problem with the Subarus is that they seem to be marketed for everybody and sales departments don’t do enough to go over potential problems and maintenance issues that are unique to AWD. People buy them, hop in and have problems because they are unaware of special concerns that were never pointed out to them.

I view them like the old British sports cars from the 60s and 70s. People knew thy were problematic, but enjoyed having something unique to talk about and tinker with. I never envied them nor Subaru AWD owners and consider these types of cars to be impractical, but to each his / her own.


The midwest is very flat. Subaru’s are popular where hills & winter conditions exist.

I Thought About That And Agree That Is A Factor, Here. Although There Are Frequent Steep Hills And Large Elevation Changes Here, We Don’t Have Many Extremely Steep Hills On Our Routes.

The hills usually aren’t a problem unless we get freezing rain (I’m not talking about drizzle) and again I don’t think AWD holds the answer because coming down those hills gets tricky and braking is the real issue. On days when it would be impossible to stand up on the highway, I have had to drive slowly with right tires on the gravel shoulder.

Again, for us the biggest problem is reduced visibility. Snow and extreme cold combine to make “snow fog” that hangs in the air. We get it frquently, that and white-out blizzard conditions. That’s when driving is most treacherous. I don’t care how many wheels are driving, the best vehicle is the one with the best radio, airbags, and lots of sheet metal, in poor visibility conditions.


I own a pair of reliable Subaru’s(interestingly turbo). They do incredibly well braking on slippery conditions as you can use engine compression to slow the vehicle at all four wheels. One major advantage of Subaru vs other AWD(except audi) is that all four wheels are under power at all times. It is also much more balanced than any FWD vehicle which will have a tendancy swing around.

The key I have learned with winter driving is no sudden movements(turn/braking) and applying braking is a delicate balance.

Subaru’s definitely are a niche car, but they do incredibly well and only have grown in sales. They had huge growth the year GM and Chrysler and other makers were in the toilet.

That being said I likely would never buy one again. I like powerful wagons coupled to a manual transmission which they no longer offer.