Back passenger tire keeps going flat

Hi all, first post here. A month ago I woke up to my rear passenger tire flat. No holes were found but I replaced the tire and wheel (as well as the 3 others) b/c I just acquired a new set. I went from the 245/70/16s to 265/70/16 bc they were Coopers and newer tires. Fast fwd to yesterday and bam....rear passenger tire flat again. And again tire is fine as I just had it filled and drove home with no issues. I will say over 40mph there is a considerable general humming noise. Could this be a bearing issue? It’s not the tire or valve. Something else??

 

It could possibly be a bad valve stem. Had the same issue on same tire, more than once.

 

Howdy from DFW and

 

Bent rim? Chance there is a crack in the alloy. Spray some soapy water all along the bead. The leak will show itself.

 

Does your tire

I second spraying some soapy water.
The hum...is it constant above 40mph or rhythmic (more like a wah wah wah)?

 

Tried the soapy water on both rims and tires. Nothing. The hum is more like a wah wah wah. Worst between 40-60mph. Slightly better over 60mph or less quiet would be more accurate.

 

I'm not a technician. However, the "wah wah wah" sound for me has been a wheel bearing for both vehicles and bikes.

 

Recently learned that gunk can build up on the inside of rim where the tire seals, preventing a good seal. If gunk present it can be removed with soap/degreaser, Emmery cloth, fine grit sandpaper, or wire wheel.
There are some youtube vids about it. You will have to take tire off rim to inspect.

There is always a chance that there is a cracked rim as well, sometimes hard to locate.

Good luck!

 

Had that happen on my X-Runner. Fortunately it was the spare and my tire light would remind me to fill it every couple of months. Efforts to clean the seal did not help.

 

Wife bought tires while I was out of town. They UPC stickers weren't removed from the tires and every 2 weeks the tires required air. Then I found that one of the schrader valves was also leaking and simply tightening it fixed the issue.
To clarify, the UPC stickers were at/on the bead and preventing the bead from sealing properly

 

One of my pressure sensors was cracked and caused a leak that wasnt fixed by replacing a valve stem

 

My guess would either be the rim is flawed or the valve stem as stated above.
Wheel bearing shouldn't have anything to do with your tire holding pressure.

 

Soapy water is your friend. Spray around the valve stem inside and outside. Sometimes schrader valves get microscopic dirt in them. Last year when I had tires mounted the tire tech ate too many marijuana gummy bears and installed the tpms wrong. Correct is black oring/washer on inside of wheel, then silver metal washer on outside that threaded collar tightens against. This moron put the silver washer on the inside, nothing on the outside and cranked the tpms collar tight. It sealed enough that it would only leak about 3-4psi a week, so I would only notice the tire bulging every 3-4 weeks.

 

This EXACT same thing happened to me on a brand new 2017 Tacoma. It would take about 3 weeks to lose enough PSI to set my TPMS light off and remind me to fill it....pissed me off to no end, but the dealer was so far away I never bothered taking it back. It was like that when I traded it in with 12K miles...

 

Have you been a good neighbor, early April fools from a friend ?
Not that I would know anybody that's done that to a friend

 

Have your mother-in-law sit on the other side.

 

All I can come up with is the bad valve or rim that's bent or cracked. I would first exchange the leaking wheel with the other rear wheel so as to definitely rule out other factors should the replacement wheel have no leaking issue. I would then replace the valve and wait to see if it still leaks. If it does, I would move on to testing the rim with tire on by immersion in a water bath while holding the wheel vertically and slowly rotating wheel looking for bubbles. And don't dismiss the tire too quickly, there may well be something small embedded in it that simply hasn't shown itself to the naked eye.

And if the replacement wheel shows up as leaking once switched, I would suspect a prankster at work. Catch'em, shoot'em, bury'em, and forget'em. Or send them a mean Valentine's Day card.

 

Just put some more Dawn soap water on that thing.

The bubbles don't lie