Slow tire pressure leak, help!

[chayos00]

So the other week I notice that my wife's car (07 Acura TL) 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.

 

[MikesToy]

You submerged your wife's tire in the tub? :lol: Your rim might be slightly bent.

 

[fourwd1]

You may have a hairline crack in the rim.
Did the pothole leave any marks on the rim?

 

[chayos00]

You may have a hairline crack in the rim.
Did the pothole leave any marks on the rim?

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.

 

[MikesToy]

Discount Tire re-surfaces rims. It beats buying another set.

 

[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. :shrug::shrug: