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-   -   Do you need to replace all of your tires?? Read first before making a thread. (http://legacygt.com/forums/showthread.php?t=105336)

blackfang 02-04-2009 08:09 PM

Do you need to replace all of your tires?? Read first before making a thread.
 
Mods, if you want to make this a sticky, feel free. If not, that is ok.

There seems to be quite a few threads dealing with damaged or blown tires to where they need to be replaced and how many do they need. I am going to expand on this.

My experience on this issue is being in the Automotive industry for 6 years and as a Subaru Service advisor. I have also worked in the tire markets as a certified Michelin/BFG Salesman.
Also, the info I am giving you is my view and facts on this subject from first hand knowledge and the failures of the AWD system due to this. If you disagree with it, then so be it, it is your car and your money. I have seen plenty of failures and people end up forking over to me their money because they made the mistake.

Whenever you have to replace any tire on a Subaru, you must measure the circumference of the new tire when it is mounted. Then you measure the old tires. If there is more than a 1/4 inch of difference in the measurements, you should replace the other tires.

Folks, do NOT let the 1/32nds or 3/32nds rule fool you. That is not the correct method and it will cost you transfer clutches. Normally the 1/4inch threshold is around 15,000 miles, but I have seen a forester make it to 19,000 and still be within 1/4 inch.

If you do not do this, you are increasing the chances of damaging the transfer clutches/center diff or prematurely wearing them out on your awd. Automatics tend to be more prone to this than manuals. It isn't really a matter of if it happens, but more of a when.


Hope this clears up any confusion on whether you need all new tires or not.

Also proper tire rotation's and frequent alignments(I recommend once a year) help prevent irregular wear on the tires. Lack of rotations can also cause awd problems as well.

TPLGT 02-04-2009 08:13 PM

Great info. I am sure this will be very helpful.

blackfang 02-04-2009 08:15 PM

Hopefully this will help some out.

fonts 02-04-2009 08:17 PM

It should help ..... but there will still be new threads. :lol::rolleyes:

blackfang 02-04-2009 08:33 PM

Possibly so, but until now there wasn't a thread addressing that, so it might reduce some of them. Definitely worth a shot.

Woodstock 03-21-2009 08:38 PM

hmmm... if I replace my 17" to 18" rims, can I still use the spare tire on my LGT? I just want to make sure. I thinks its a NO?

PhilT 03-21-2009 08:48 PM

When you measure the circumference, do you have the car in the air ?

I would be interested to know how much a couple of psi difference between tyres makes on the circumference.

Mr. Sinister 03-21-2009 11:34 PM

Quote:

Originally Posted by Woodstock (Post 2364386)
hmmm... if I replace my 17" to 18" rims, can I still use the spare tire on my LGT? I just want to make sure. I thinks its a NO?

Heh. I see you've done a search and found this thread. Post the tire size selections that you made and maybe blackfang will chime in.

Woodstock 03-22-2009 06:04 AM

225/40/18 on a 18x7.5 48+

devobuzz 03-22-2009 07:27 AM

Quote:

Originally Posted by PhilT (Post 2364398)
I would be interested to know how much a couple of psi difference between tyres makes on the circumference.

I had the exact same question. On long trips I'll be carrying a full size spare with no wear on the tread. This will make the tire slightly larger than the stockers. I figured if I run it with 5 psi less air it will make up for the difference in circumference. But I have no idea how much air pressure difference to use.

blackfang 03-22-2009 08:05 AM

Quote:

Originally Posted by Woodstock (Post 2364386)
hmmm... if I replace my 17" to 18" rims, can I still use the spare tire on my LGT? I just want to make sure. I thinks its a NO?

The spare is just used to get you to a place to fix the tire/replace. If that is all you are going to use it for you will be ok. Now if it is going to be on there for more than a few days, that is a no no anyways.

Quote:

Originally Posted by PhilT (Post 2364398)
When you measure the circumference, do you have the car in the air ?

I would be interested to know how much a couple of psi difference between tyres makes on the circumference.

You need it off the ground enough to get a tape measure around them for an accurate reading. Once the new tires are mounted on the wheel and inflated, you measure the circumference of it. Then measure all the rest.

Woodstock 03-22-2009 07:59 PM

cool thanks!

phenryiv1 04-15-2009 06:11 AM

I am going to bump this, rather than making a new thread for a related question-

I am at ~25K on my 08 and am still on the stock tires, which I rotate every 6-8K. For summer, I want to run some 3-season tires, so I am considering different options.

I had an E36 with M3 rims, which are staggered. I sold the rims with the car (stock rims were on it, with A/S tires), and trashed the rears, which were useless. I now have 2 good (formerly front) tires with about 3/4 tread. A guy an hour or so from me has a pair of the same tires (brand, sizes, model, etc.) will approximately the same mileage. What is my margin for error as far as differences between the pair that he has and the pair that I have?

08 2.5i, if it mattters...

krzyss 04-15-2009 08:50 AM

RTFM

You should see magical value of 1/4 of an inch.

It is allowable difference in circumference.

Krzys

darkfox1 04-15-2009 09:38 AM

:munch:

"wearing out" tires is not something that has happened to me in 60k miles. I keep damaging mine somehow. :spin:

great thread btw. I've wondered this but I replace all 4 tires every time.


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