chayos00

So the other week I notice that my wife's car has a tire that is reading a lower than normal tire pressure. I always inflate the tires to precisely the same pressure between the right and left side (front and front then back and back tires). I keep the fronts at 33-35 psi and the rears to approximately 2 psi lower.

I found the front two tires at 29 (RF) to 34 (LF) psi. So I re-inflated the tire and again about a week later I found it at the same ratio to one another. I inspected for any nails or any other damage, I found nothing. Tonight I took it to a tire shop but I got there just as they closed. He did another basic inspection and also found nothing. Used some soapy water and nothing. So he mentioned coming back tomorrow so they can submerge the tire. Well I did this on my own tonight at home, filled the tub and filled a 5 gallon bucket with some river rock and submerged it. I inflated the tire to the max sidewall pressure of 44psi, (it's the factory Michelin Pilot MXM4)

After now about 3 hours I see nothing, no stream of bubbles, nothing from the valve steam or around the rim of the tire. The tires have just shy of 39K on them.

About 3 months ago my wife hit a big pot hole with no damage, but I'm wondering if maybe it is the cause of this slow leak.

Any idea's guys? Yes the TPMS pressure versus a gauge pressure reading is identical.

Turbonut

iTrader: (1)

A slow leak is very difficult to find, start by tightening the TPMS nut very slightly and if that doesn't help, a water tub is the way to go. When in the water, keep it on one side, then turn it over.

VQPower37

if she hit a pot hole, maybe the wheel is bent causing a slow leak

chayos00

I'm questioning the same thing. But the leak didn't start right away, it was like over a month or 2 from when she hit it.

There is a dark mark from the rubber when it hit the pot hole. You can clearly see the impression (black rubber mark) from where she hit the front to back.

I wish I took a picture of it, as the mark on the inside of the rim is more pronounced than it is from the outside. I'll see what i can do about a picture.

I hate cars

Sometimes when it leaks around the bead, adding more pressure can seal it up. Many times it might have a slow leak and as the pressure gets lower it leaks quicker. You may have sealed it up by inflating to the max. You can always try a higher inflation pressure to see if it seals it.

I had a friend with a 3 series with the same issue. If the tires were just a little too low and hit 28psi it would be a nearly instant flat. If they were around 42psi we could do a 4 hour road trip with no issues. His problem was flaking chrome in the bead area.

EndleszgenTL

your valve stem could be dry rotted causeing it to leak.. if its regular and if its tpms the seal just likes to mess up anyways. or you need to reseal the tires.. take it to your local tire shop.. they have the proper lube/paste to reseal the tires. or u could have a very small nail too. or noticeably cracked rim.

OneWickedTypeS

I had a similar issue once, we had the tire place check it 3 times with no luck. Than we started talking about what we would need to do to warranty the tire and than they found that not only had she bent the the rim but it was also cracked and that was were the leak was coming from...

chayos00

****UPDATE****

Finally got the car to a tire shop, told them all that I have done to check it with finding no leaks. Basically submerging the entire tire in water for 3 hours and watching for bubbles.

So they unmounted the tire looked at the rim, saw no visible damage (I was looking too) or out of roundness. The guy looked and felt along the entire inside of the tire found nothing. He pointed out the spot where the tire steel belts were "damaged" by the pothole, just slightly kinked in the rubber, but saw no cracks in the rubber. The TPMS sensor was 100% tightened, and obviously the valve stem innards were reseated when the tire was re-inflated.

So we remounted the tire and I was off on my way, we'll see what happens, hopefully the bead was just jarred by the pothole and remounting it fixes it.

Turbonut

iTrader: (1)

If there is evidence of belt damage, replace the tire whether the carcass is damaged or not.

pohljm

Perhaps it was just the onset of the cold weather. around this time of year my tire pressure warning goes off because of the low temperatures. just reinflate to the pressure you want for the cold months

chayos00

I found the front two tires at 29 (RF) to 34 (LF) psi. So I re-inflated the tire and again about a week later I found it at the same ratio to one another.

I continue to loose about 5 psi every 1-2 weeks. It's not the "winter" change. Plus I live in Arizona it's still warm here.

chayos00

Okay, the guy at the tire shop didn't seem concerned about this. I'm not doubting you just would like to know why it should be replaced?

DMZ

I've had similar issues. In one case, the tire shop guys couldn't find a leak no matter what they did so they had to coat the edge of the rim that black bead sealer goop all the way around the circumference of BOTH sides of the rim before remounting the tire in order to stop it.

Other times, bent or cracked rims courtesy of NYC area roads were to thank.
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chayos00

I saw the guy remount it, they put some sort of goop on the bead when he remounted it. Not sure what color it was.

I will know the true answer in a few days, by Monday I'm sure.