I found this to be a bit curious...after months of sitting, I noticed the left rear tire on the Bronco started to buldge a bit. I chalked it up to the 40-50* temp drop. Over the next couple of days it loses alot more air. I keep the tires on the Bronco inflated to 42psi, when I aired up the tire it was at 8 psi. I aired up the tire with the expectation of discovering a slow leak. It's been a couple weeks now, and been driving the Bronco that whole time, and no air loss at all. I don't believe anyone wanted to steal my tire air, and I figured if it was a temp correlation it would affect all the tires (but certainly not 34psi). Maybe sitting all that time exposed a weak spot? Anyone have an explanation for this? Like I said, I just found it curious because I've never known for a tire to leak then be ok.

Many times when they sit, tires do lose some air. Typically it is from the bead. When you run it, the bead seals up from moving. I see it all the time.

Interesting...so what happens at the bead that just lets the air escape like that?

Just a guess not 100%
some times a small amount of rust/corrosion occurs letting the air leak out slowly.
Other times I thing the rubber just deforms a bit from the weight up on the tire and it leaks.

It is strictly a pressure seal, so air can slip by through any imperfections between the tire and rim. Doesn't have to be very visible. Aluminum rims in my experience are the worst offenders. Any kind of corrosion will speed it along as well. The rubber is sealed by pressure, so the air molecules being smaller can slip by if there is any kind of opening at all. By driving it, the bead actually wiggles around just a little, and will reseat.

Roger and Randy are right - it is minor corrosion around the bead seating area of the rim .
Whenever i was doing tyres in the workshop we would clean up the seating area of the rims with a wire brush to knock off the loose corrosion and then give it a quick buff up to get rid of the rest ..... one of the causes of corrosion on steel rims is people using dishwash liquid to "lube" up the tyre before fitting - tyrefitters should always use a proper compound such as "tireslip" which contains an anti-corrosion agent ... that will also slow down oxidation on alloy rims too.

kiwi f150 said:

Roger and Randy are right - it is minor corrosion around the bead seating area of the rim .
Whenever i was doing tyres in the workshop we would clean up the seating area of the rims with a wire brush to knock off the loose corrosion and then give it a quick buff up to get rid of the rest ..... one of the causes of corrosion on steel rims is people using dishwash liquid to "lube" up the tyre before fitting - tyrefitters should always use a proper compound such as "tireslip" which contains an anti-corrosion agent ... that will also slow down oxidation on alloy rims too.

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I used Dawn dish washing liquid.


Wheel barrel tire are the worst for beads leaking.

That's why tube every wheel barrel tire. They seem to go flat so easy ad are a pain to get them to take air.

I actually have gone to using protectants like Armor All to mount tires. Slick and non corrosive.

m78 said:

Wheel barrel tire are the worst for beads leaking.

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I lost most of the hair on my right forearm once, when trying to seat a wheel barrow tire...guess I used a little too much starting fluid.

Ya know, I always thought that was crazy, but in AZ one of our equipment trailers had 14.5" wheels (mobile home style) and if those damn things were even a little low on air they'd pop loose of the rim. and they were a bear to get reseated.

so we were out on the job one day, I was loading up the backhoe so we could leave and we notive one of the trailer tires is flat. jack it up, start the compressor, and fight with it for 15 minutes and still no luck. The guy that was with me got some ether and a torch out of his truck and said he'd get it. I'll be damned if it didn't work perfect too...

I've actually had to do that a few times... can be a bit scary, and you have to be fast with the air chuck or have to do it again.

Fellro said:

I've actually had to do that a few times... can be a bit scary, and you have to be fast with the air chuck or have to do it again.

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Yeah...biggest tire I've been successful doing it with was a 32x10.5x15 on my bro's Jeep. I haven't been able to get a bigger tire seated...not enough air and not quick enough, but I've seen guys do it with upwards of 38" tires.

Hairspray will do it in a pinch too ...... much to the wifes disgust when i flogged hers for an emergency reinflate one day.

Basically what everyone else said. Same idea as when a walkbehind mower or lawn tractor sits for an extended period of time. I wouldn't worry too much. If you have no problems when driving it continuously you should be fine.