Can you replace a single tire on Forester or have to replace all 4?

[Boris Dynin]

Hi,

My understanding is: if one tire is damaged you have to replace all 4 of
them on AWD vehicle (Forester). Is this true?

Thanks,
Boris

 

[Tony Hwang]

Hi,
Once I replaced only one tire on my '90 Legacy. The tire went flat and
disintegrated into pieces. I replace it with identical tire and did not
experience anything negative. I'd think there is some tolerance factor.
Nothing is 100% precision.
Tony

 

[Luke Gallagher]

Hi,

I would recommend replacing the tyre with one that is as close as possible
to a match for the other ones. If there is a significant diameter difference
(ie tread depth) the 4wd can get a bit wound up. This is why your meant to
put subarus into 2wd when using a spare/space saver. But as long as the tyre
is close to the others it should be fine (ie same size & similar tread
depth).

luke

 

[Victor Roberts]

Hi,

I would recommend replacing the tyre with one that is as close as possible
to a match for the other ones. If there is a significant diameter difference
(ie tread depth) the 4wd can get a bit wound up. This is why your meant to
put subarus into 2wd when using a spare/space saver. But as long as the tyre
is close to the others it should be fine (ie same size & similar tread
depth).

Tire manufacturers usually list the outside diameter of the tire in
their detailed specifications. I found it quote interesting that tires
of similar "official" size could vary by more than 1 inch in outside
diameter. If the outside diameter of the new tire matches the old one,
then he should have no problem. However, if the old tire is used, then
he will have trouble matching the diameter with a new tire.

 

[Edward Hayes]

My 2000 Forester had a spare identical to the 4 on the ground so I
transferred the spare to replace the flat tire. The flat was about 1/2 gone
and I noticed no problems. All tires were then changed when worn out. Eddie

 

[Bill Putney]

Tire manufacturers usually list the outside diameter of the tire in
their detailed specifications. I found it quote interesting that tires
of similar "official" size could vary by more than 1 inch in outside
diameter. If the outside diameter of the new tire matches the old one,
then he should have no problem. However, if the old tire is used, then
he will have trouble matching the diameter with a new tire.

1" difference in diameter for same nominal size? That's huge. You sure
about that Vic? Can you guve some examples?

Bill Putney
(to reply by e-mail, replace the last letter of the alphabet in my
address with "x")

 

[Pète Ð]

Bullshit, total crap. This is a Forester it is all wheel drive all the time,
you cannot put it into 2WD unless you remove the drive shafts. Wind up ????
It has a diffon each end and one in the middle, it can't wind up, not
possible.

 

[Losiho]

Bullshit, total crap. This is a Forester it is all wheel drive all the time,
you cannot put it into 2WD unless you remove the drive shafts. Wind up ????
It has a diffon each end and one in the middle, it can't wind up, not
possible.

You can put an automatic Outback into 2WD just by pulling a fuse in the
engine compartment.

 

[Dan Duncan]

Tire manufacturers usually list the outside diameter of the tire in
their detailed specifications. I found it quote interesting that tires
of similar "official" size could vary by more than 1 inch in outside
diameter. If the outside diameter of the new tire matches the old one,
then he should have no problem. However, if the old tire is used, then
he will have trouble matching the diameter with a new tire.

Different pressures in the same type of tire will also change
the diameter.

-DanD

 

[Dave Null Sr.]

You can put an automatic Outback into 2WD just by pulling a fuse in the
engine compartment.

You add the fuse.

 

[Al]

Different pressures in the same type of tire will also change
the diameter.

Some tire resellers will "shave" your new tire to match your other
three. They measure the circumference of each tire and shave them all to
match. You lose a little in mileage. Beats having to buy a complete set
or damaging your xmission.

Al

 

[Bill Putney]

Well, with a limited search I found outer diameter differences up to
0.8 inches.

All are 205/70R15 Diameter (in)

Michelin Destiny 26.1
Michelin Symmetry 25.8
Nokian NRE 26.3
Nokian WR 26.3
Dunlop SP40 26.4
Bridgestone Turanza LS-T 26.6
Bridgestone Weatherforce 26.3

Hmmm - tirerack.com's sheets show the Michelin Symmetry at 26.1, but
even with that, it does indeed indicate 1/2" difference in diameter.
That's about 2% difference, but still more than I would have thought.
Thanks for pointing that out.

Bill Putney
(to reply by e-mail, replace the last letter of the alphabet in my
address with "x")

 

[Lance B]

You add the fuse.

Different pressures make very little to no difference to the rolling
circumference to a tire. The circumference of a tire changes little as
it is a fixed value. The only difference pressure makes (when there is
less pressure in that particular tire) is to drop the side wall of
that tire so that the axle is now lower. This gives the feeling of
pulling to that side. Pressure difference makes little difference to
the AWD set up, although I would recomend having your pressures
correct all round.

There has been some discussion as to the circumference difference to
tires used on Subaru AWD's. There has been suggestion, I think from
Subaru, that it should be a max 4% difference between tires. This is
actually quite a lot of difference when you calculate it out. If you
take a tire of 215/60 16, which I think is fitted to a Forester, its
overall diameter is 664.4mm (we will stick to diameters as it is
easier to show and Pi is a constant so it makes the same comparison as
circumference). If you calculate 4% less than 664.4mm you get 637.8mm.
This is a difference of 26.6mm or 13.3mm on each side of the rim
(remember there is tire on each side of the rim diameter). Now, an
original tire is has about 8mm of tread, so therefore, even if you
wear it out to nil tread (not recomended) you only take off 16mm (8mm
x 2 per side of diameter). I think you are supposed to renew a tire
when it gets to 1.5mm tread left by law, which means you will end up
with 13mm of tread wear overall and by this time you will need to
replace all tires!

So, you should be able to replace one tire with no worries as long as
all the others are not near their end of tread life of 1.5mm.

 

[John Varela]

You can put an automatic Outback into 2WD just by pulling a fuse in the
engine compartment.

But the poster asked about a Forester.

 

[Ken Gilbert]

Where does the 4% tire circumference difference come from?? I have read that
the IDEAL circumferential difference should be 1/4 inch MAX. Eddie

bit of a discussion over here:
http://forums.nasioc.com/forums/showthread.php?s=&threadid=381351

ken

 

[Mike B.]

Three bald tires and one new. Not good. No tires wear identical. Would
suggest new tire go on back to keep you from having steering drift.