Slow pressure leak in cold weather only - solved

[abc]

One of my tires was driving me crazy. It would only lose pressure when the temperatures got cold outside. Parked in the garage it barely lost a pound a week.
So I had the mechanic look at it. In the warm garage, the bubble chamber showed no leaks. We said its gotta be on the rim.
sure enough. The alloy wheel had corrosion all around, it look like salt scum. They cleaned it and re-seated the tire and no more leak.

Considering how corroded it was, I'm pleased that the tire had enough flex to not leak most of the time. I have Coopers on right now.

 

[Fivefingerdeathpunch]

See it everyday on almost every car that we take tires off of.

It's crazy how much corrosion can be on the rim and tire and it still wont leak.

 

[Scottydoggs]

all my wheels have bead sealant on them now because of this corrosion on the wheel lips. had a few go flat over night from it.

 

[industrialfish]

And vast majority of places that mount tires don't take the time to properly clean the bead/lip so that accelerates any problems. While it may take me 4 hours to do 4 tires at home, I can guarantee that after I've cleaned them and properly used bead sealer that the ONLY reason they'd be leaking again is from a puncture.

 

[bobc455]

all my wheels have bead sealant on them now because of this corrosion on the wheel lips. had a few go flat over night from it.

I have seen the bead sealer cause corrosion (virtually every time it is used).

I will typically grind through the old corrosion with an abrasive of some kind, then paint the bare rim with a clear-coat. Let it dry for a day or two, remount the tire, and voila.

If I don't have time for a clear coat, I will just grind through the corrosion and mount the new tires. We have an abrasive wheel (typically for body work) on a drill set up by the tire machine for this purpose. Typically adds about 5-10 minutes per rim.

Another thing to watch for is bad valves. There was a huge batch of bad valves from China about 6-8 years ago. Most of them have been replaced by now, but I just had a guy a couple of months ago with all four wheels leaking...

-BC