Subaru Outback Forums banner

1 - 6 of 6 Posts

·
Registered
Joined
·
50 Posts
Discussion Starter #1
This subject must have been brought up before but I was unsuccessful in a search.

I've just noticed that the previous owner of my Outback decided to replace one of the tires with a different brand. :mad: The tread pattern is similar, but as expected the tire has more tread remaining than the other three.

How serious of a problem is this? Should I suspect serious damage considering it is likely that several thousand kms of use in this configuration?

Is there a way to test the AWD system for correct operation?

Thanks for your thoughts.
 

·
Superb Moderator, ,
Joined
·
6,194 Posts
It should only matter if the tires are on the same axle. You want the overall ride height the same. Front to back doesn't matter, that's the way the tires should be rotated.

But Subaru wants equal height on tires across from each other on the same axle, different axle revolutions all the time are bad is what they are trying to tell us. It's like going in a circle permenantly on a skid pad, the outside tire is rotating faster than the inside tire. It may be good for turns and such, but not all the time. Brian
 

·
Registered
Joined
·
32 Posts
Phobos said:
[B Some item snipped away...
The tread pattern is similar, but as expected the tire has more tread remaining than the other three.

How serious of a problem is this? Should I suspect serious damage considering it is likely that several thousand kms of use in this configuration?

Is there a way to test the AWD system for correct operation?

Thanks for your thoughts. [/B]
Well the thing that really matters isn't the amount of thread left but the actual circumference of the tire in question, e.i. if deeper grooved it's possible to have "more left" but still be the correct circumference. Anyway, just measure and be....
How to test...
If you lift it, the car that is, enough so that all 4 wheels are free from ground contact an initial test should show all 4 wheels turning over if the car is put into gear/drive. You could additonally if available/possible deliberately put one/either axle onto something really slippery, mud, ice, snow or what have you and if the 4WD is intact the wheels that have good traction should pull the car free.
Regarding the location of a "wrong sized" tire I'd say nowhere! Eventhough most of the stress in all likelyhood will be put onto the closest differential even the centre one and visco coupling or other distribution device will be strained, as it will percieve things as one end/axle is somewhat losing traction, and hence rotates at a somewhat higher rpm. This will make the centre one try to redistribute power/torque fwd/aft.

But, do test first and worry later.
 

·
Registered
Joined
·
50 Posts
Discussion Starter #4
Thanks for the replies.

I will try to measure the tire circumference and see what the difference is.
 

·
Registered
Joined
·
32 Posts
Phobos said:
Thanks for the replies.

I will try to measure the tire circumference and see what the difference is.
If they match your're probably in the clear but you might want to check that AWD works just to make sure.
If they do differ, I'd say you should contact an authorized garage/workshop and get their opinion on the matter. For instance what percentage -of circumference- might be acceptable or outright stupid to use;) Most likely they'll be able to diagnose your car's AWD if you'll want them to, for a fee though :( I would think.
Then, if they do differ get a "new" set of matching wheels/tires.Used or brand new doesn't matter as long as they match. This way you'll cease putting unnecessary strain on the AWD's power/torque distribution. If a new set of wheels isn't an option at the moment then stop using the car 'til it is. As a kind of band-aid move if you absolutely must use the car I agree that putting the odd wheel out onto a axle without a limited slip differential is probably a wise move i.e if that's an option.
 
1 - 6 of 6 Posts
About this Discussion
5 Replies
4 Participants
hkan
Subaru Outback Forums
Welcome to the Subaru Outback Owners Forum, we have tons of information about your Subaru Outback, from a Subaru Outback Wiki to customer reviews.
Full Forum Listing
Top