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2009 Subaru Legacy Limited - TPMS Light

34 messages,  Last post on Feb 12, 2011 at 7:22 PM

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What is this discussion about? Subaru Legacy, Subaru Outback, Sedan, Wagon

Messages Page 2 of 4

#5 of 34 Re: 2009 Subaru Legacy Limited - TPMS Light [pilot1226] by xwesx

Feb 17, 2010 (4:19 pm)

Replying to: pilot1226 (Feb 17, 2010 2:47 pm)
The bead is essentially the contact between the rim and the tire. When air pressure is applied to the inside of the tire, it forces the tire against the lip on the rim and creates a seal. When the rim's lip is bent, it can result in uneven pressure on this sealing point and allow air to leak. A bead sealer acts as a gasket between the tire and the rim to help ensure a seal. It does not actually fix the bent rim, but it can prevent the tire from leaking at that point.
 
It is entirely possible that the leak is coming from this rim and cold weather would certainly exacerbate it. When things get cold, they shrink.
 
OEM rims are ridiculously overpriced. If you can find a rim off a wrecked example for a reasonable cost, that would be the way to go. Otherwise, you could likely get a full aftermarket set for much less than $1000. It is not a time-critical issue, though, as long as you are aware of it and continue to check the pressure in that tire.

#6 of 34 Re: 2009 Subaru Legacy Limited - TPMS Light [pilot1226] by fibber2

Feb 17, 2010 (4:27 pm)

Replying to: pilot1226 (Feb 17, 2010 2:47 pm)
I think it is likely that you have identified the cause...
 
The bead seal is where the stiffened edge on the tire has to make an airtight seal against the inner lip of the metal wheel/rim (alloy or steel). In the old days, or on most bicycles, the air is held in by an inner tube. "Tubeless" technology relies on a rubber to metal seal to do the same. During mounting, a slippery water based glue helps promote the seal, and from then on, air pressure holds it all in place.
 
If the wheel no longer has a perfect mating surface, a more potent glue is used. But if everything is too compromised, large changes in shape (think winter) could pull it very slightly apart. Or, it could have even developed a hairline fracture that is giving way over time. If it was visibly damaged in the pothole incident, you should be able to see and identify which one. If it is this rim, you need to replace it, NOW! Please realize that you are playing with fire. A sudden a blowout and crash will ruin your whole day.
 
I would expect the cost of an OEM alloy wheel probably runs about $300 - $450. You might be able to find one cheaper on-line. Steel wheels are under $100. A quote of $1000 sounds crazy!

#7 of 34 Re: 2009 Subaru Legacy Limited - TPMS Light [xwesx] by fibber2

Feb 17, 2010 (4:30 pm)

Replying to: xwesx (Feb 17, 2010 4:19 pm)
Hey Wes! I got interrupted, and when I finished and posted, you got there first. Only thing I disagree with is the urgency. Not knowing why it is losing pressure would prompt faster action on my part. Then again he does have TPMS to tell him when disaster is imminent.

#8 of 34 Re: 2009 Subaru Legacy Limited - TPMS Light [fibber2] by pilot1226

Feb 17, 2010 (5:29 pm)

Replying to: fibber2 (Feb 17, 2010 4:27 pm)
Thanks for the info. I'll check the number on the tires tomorrow in the morning and see if it's the one that was replaced. We were told that the rim was bent - we didn't see it. The only visible markings we saw on the rim itself was the distinctive pothole marking from when the tire "rubs" against the rim, leaving a black mark.
 
I'm a pretty big fan of the OEM rims and I'd prefer to keep them all consistent, though I did see on some websites that I can get them individually for around 125-175.
 
On the off chance that this is a different wheel we're talking about, I'm slightly irked at the fact that this is now the second Yokohama I've had an issue with in the last year and a half I've owned the car.

#9 of 34 Re: 2009 Subaru Legacy Limited - TPMS Light [fibber2] by xwesx

Feb 17, 2010 (5:29 pm)

Replying to: fibber2 (Feb 17, 2010 4:30 pm)
Yeah, I caught that, and it is a good point. I was not considering the possibility of a compromised rim (in other words, the aluminum alloy is cracked). That could definitely give out in a catastrophic manner especially if the leaking is a result of the fatigue growing worse and not a result of winter shrinkage compromising the bead.

#10 of 34 Re: 2009 Subaru Legacy Limited - TPMS Light [pilot1226] by xwesx

Feb 17, 2010 (5:32 pm)

Replying to: pilot1226 (Feb 17, 2010 5:29 pm)
It may be that the quote you received was for a set of four, not a single rim. I would think the price you listed of $125-175 is much more accurate for a single rim. If you go with OEM, there would be no reason to replace the whole set.
 
Of course, if you hit a pothole, wouldn't two tires/wheels be affected (front and back)? Maybe the problem now is from the tire on that side that was not replaced the first time around.

#11 of 34 Re: 2009 Subaru Legacy Limited - TPMS Light [xwesx] by pilot1226

Feb 17, 2010 (6:25 pm)

Replying to: xwesx (Feb 17, 2010 5:32 pm)
I suppose anything's possible. We live in Northern NJ so it's pothole central up here, and the constant snow accumulation & plowing certainly isn't helping them go away.
 
My wife and I were pretty stunned when we were told it's typical pothole damage to the tire & rim, because neither of us (she is the primary drive, though I do take it from time to time) recalled any "jolting" potholes like they were describing.
 
I'll keep that in mind when I check the tires tomorrow - since rotations follow a standard path, I'll see if it was "behind" the front passenger side that was actually damaged. I'll go dig out my paperwork and find out how many rotations I've done. Pretty sure I've done 2 so far - 7500 and 15000. So, it all depends on where they mounted the replacement.

#12 of 34 Re: 2009 Subaru Legacy Limited - TPMS Light [pilot1226] by fibber2

Feb 17, 2010 (6:42 pm)

Replying to: pilot1226 (Feb 17, 2010 6:25 pm)
It's good that we're 'double teaming' this, as Wes brought up an excellent point to look at the other tire on the same side as that might be the current leaker.
 
OEM wheels are way overpriced. I bought respectable looking alloy rims from TireRack for both our Outback and Honda Odyssey with snow tires (I live a 100 or so miles north of you). A set of 4 was cheaper than a single OEM rim for either vehicle.
 
Remember a couple of rules regarding Subaru AWD systems:
1) Rotate front to back - do not cross (I never understood this one, but it's what they say).
2) Tire circumference must be close to the same all around to not put stress on the center differential. See your owners manual for details. They recommend replacing tires in pairs if there is a substantial difference in thread depth.

#13 of 34 Re: 2009 Subaru Legacy Limited - TPMS Light [fibber2] by pilot1226

Feb 18, 2010 (7:00 am)

Replying to: fibber2 (Feb 17, 2010 6:42 pm)
I'm almost positive that my tires are not directional and follow a standard rotation pattern. Either way, I've done all my rotations at my Subaru dealer nearby, so if that was done in error, it's their problem.
 
I'm familiar with the circumference issue. It seems like the spare tire is 16" whereas the other tires are 17". I remember reading the owner's manual when we first got the car and it included instructions on disabling the AWD via a fuse.
 
Alright, out to the car now to see the which was replaced.

#14 of 34 Re: 2009 Subaru Legacy Limited - TPMS Light [pilot1226] by pilot1226

Feb 18, 2010 (7:38 am)

Replying to: pilot1226 (Feb 18, 2010 7:00 am)
Service Papers in hand and pictures of the tires...
 
12/15/08 - 3750 mi service
04/14/09 - 7500 mi service (Tire Rotation)
04/16/09 - Passenger Rear Tire replaced (sidewall bubble)
07/24/09 - 11250 mi service
11/10/09 - 15000 mi service (Tire Rotation)
 
So, looking at the pictures:
 
Passenger Front: fdh4 nxf4907
Passenger Rear: fdh4 nxf4907*
Driver Rear: fdh4 nxf1908
Driver Front: fdh4 nxf4907
 
So, we can see that the Driver Rear tire is the one that was replaced as this DOT number matches my documentation from the shop where I replaced the tire. Given the 2 rotations, it appears that the replaced tire has followed the typical rotations per the Subaru owner's manual below:
 
[IMG]http://i48.photobucket.com/albums/f203/disregardec/subaru.jpg[/IMG]
 
Whether the dealer actually follows this or not, I don't know. I know that my previous car, a Civic, had a different rotation path even with non-directional tires.
 
So, it seems like between the two rotations, the passenger rear went to the driver front, then the driver rear where it is now.
 
This means that the tire with the persistent TPMS light was on the Driver Rear at the time the other had the sidewall bubble - on the other side of the car. So, to me, this rules out mauling a curb or the same pothole being the culprit. Again, a lot of this "theory" depends on whether or not they were rotated the way the owner's manual said, but so far, all my rotations have been done by the dealer. And, we ruled out that it's definitely not my new tire that's leaking, which is a relief.
 
I didn't see a nail or anything irregular in the treads themselves. Either way I'll have the dealer look at it when I take it in for the 18,750 mi service next week.

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