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I have an SUV with factory 16" steel wheels and P235/70R16 tires. The tires have just under 30,000 miles of gentle driving on them. Two of the tires have been leaking quite a bit (about 10 psi per week). I brought the vehicle to two different reputable independent mechanics, and they took the tires off, and couldn't find a problem. They applied bead sealant (which I know is controversial). Both also replaced the valve stems as a guess after they couldn't find leaks in the tires anywhere. I also checked for leaks myself with soapy water in a spray bottle.

If the professionals couldn't find leaks anywhere, what should I do next? Should I bring it to additional shops until someone can find the problem? Are the mechanics looking in the wrong place? Could the wheels be the issue? They seem to be in decent shape from what I can see.

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Have you had your rims checked for cracks or corrosion? –  Cᴏʀʏ Mar 10 '11 at 2:16
Have they tried changing one of the suspect tires with a "known-good" tire from another wheel? –  Iszi Mar 10 '11 at 3:34
I don't have a useful answer but just wanted to say Wow - 30,000 miles from a set of tyres! If I get 12,000 I'm delighted. –  Rory Alsop Mar 10 '11 at 22:00

5 Answers 5

up vote 15 down vote accepted

My wife had a similar problem on her car and it turned out the problem was the wheel, not the tire. We'd had enough sand and salt on the road this winter that she had corrosion / gunk building up right at the bead. The tire shop dismounted the tires, cleaned up the seating area on the wheel and then remounted the tire. The problem now seems to be solved.

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i would second this. The rims are suspect. –  NoCarrier Mar 10 '11 at 3:32
I've had gravel and grass manage to get in the bead area and cause a leak before. –  Brian Knoblauch Dec 2 '11 at 20:01
A few months ago, I brought the vehicle in to the shop again, and they tried a grinder to clean up some rough areas on the wheel, reinstalled the tires, and they've been leak free since! –  SomeGuy Mar 15 '12 at 14:07
@SomeGuy, congrats! It always feels great to check off problems like this as "done!" –  Bob Cross Mar 15 '12 at 17:31

You'll need some sort of a tank where you can submerge the entire wheel/tire - a small pool will do, although if you're in the northern hemisphere that might be a bit of a challenge this time of the year.

Put the whole wheel underwater, and see if you can spot any bubbles.

I have seen some shops that have a tank they can put part of the wheel/tire into, but I don't think they usually cover the wheel. This is one case where you may have to do it yourself.

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Definitely try isolating the wheel. I spent quite a long time with a previous car trying tires and valve stems and mounting issues. Eventually I replaced the tires and still had the same problem on the same wheel, and replaced the wheel, and it was fine after that. In my case it would take 2 to 3 weeks to get low, so it was a fairly small leak.

My tire shop did say at one point at that it might be cracked, but they couldn't tell for sure.

In my case I got the spare wheels on ebay fairly affordably, despite being crazy chromed ones. 2 of the 4 I got were bad as well, but among the 8 they were able to come up with 4 good ones. :-/

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I have heard of cases where low quality,I hesitate to use the word cheap have actually had porosity issues.The air is leaking through the aluminum casting.Most of the time is spent looking at the tire and the bead area and the leak is on the back side that was not sprayed with a clear finish.

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Alloys tend to lose air after a while due to corrosion on the rim/tyre junction. In the past I have taken them to an engineering company who will skim the rims back to perfection. Problem solved but did cost £35 per wheel.

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