Inside Rear Tires Leaking Air Any Thoughts?

[Rich Franklin]

I bought new Michelin's (DOT 2012) last year and for some reason I keep losing a considerable amount of air (25-50 psi per week when sitting) from my inside rear tires. I suspect that it may be because the valve extenders (rubber) they installed however they were all that was available at the time. I've made arrangements to have them inspected and replaced if necessary but was wondering if there could be anything else. I think it's pretty unlikely that both inside tires could've developed a leak simultaneously from a nail, etc., but stranger things have happened. Any thoughts?

Rich

[ccjohnson]

Other than leaking valves, one possibility could be dirty rims resulting in poor bead seal.

[The Newell]

Valve stems and extenders are common items, independent of the tire make. However, I would recommend replacing rubber extensions with steel ones. It's very possible that it's the rubber extensions that are leaking.

[folivier]

Are you sure they put new valve stems when they changed the tires? That's a common problem, new $600 tires with old valve stems. Rubber gasket on the stems will dry out and leak. Had it happen before and just had it happen with 6 new tires when we bought this one. Made them redo it.
Another thing is the extension should only have pressure when you depress the valve stem to check it. Unless you have tire monitors then they will stay pressured up. I had to take off the extensions on my '93 when I added tire monitors since they would leak.

[Chester B. Stone, Jr.]

A word of caution when replacing rubber extensions with steel one. The steel extensions should be supported with a rubber or plastic insert into the wheel opening or the constant vibration will weaken the valve stem.

[Newell Attack]

Valve extenders are not made for tires, they are made for valve stems and those are all the same size thread and such so they are universal.

They do, however, have a tendency to leak especially if not properly tightened. Also, sometimes they do not check the nut that holds the valve stem to the rim, those leak too.