loud humming noise, tires deflating, wheel paint is bubbling

I have a 2000 4 runner, well maintained, only 130k miles, 3 year old tires. About a year and a half ago I noticed my tires were getting pretty low on a regular basis, I was putting air in them about every 3-4 weeks. 3 out of 4 of them always needed air. Several Schwab employees told me it could be because of the changes in weather. Well?..... I should say that year I did move up to the high desert so the summers were hot and the winters were snowy and cold. It didn't really make sense to me but I went with it .. because I really know nothing about wheels or tires. I've had cars for about 40 years and have never experienced this ....phenomenon. Then I notice my wheels were getting louder, hard to explain the noise, but I can say what it isn't.... no vibrating, no grinding, no clicking, it's almost like the sound they make when you have studs on or really low tires, kinda of a hollow loud echo noise.. sorry that's the best I can do. I had 2 different mechanics point out some bubbling of the paint around the center the wheels as if they were getting very hot and the latest one said that was probably the cause of my tires deflating.

So after reading through some of the threads I had a thought.... I'm thinking that the axles or wheels or bearings or something down there were getting hot and that was causing my ties to lose air? At some point I noticed my wheels getting louder and not long after that a mechanic noticed the bubbling on the wheels. I'm fairly certain they noise, bubbling and deflating tires are all related. What ever the problem is it seems to be getting worse, I've had it looked about 4 times now during my regular maintenance over the last couple of years both at a tire center where I bought the tires and at the dealership and no seems to think there's a problem, or maybe it just hadn't surfaced yet?

If anyone has advice on what I can ask them to look at specifically I would greatly appreciate it.

 

Do you have any details on your tires/ wheels, wheel bearings? Pics? Modifications?

 

There have been no modifications, everything is stock, The tires are Wild Country. I can take pics of the wheels/bubbling. Thanks.

 

If the wheels are old, there may be some rusting or corrosion on the inside edge where the bead is. Sometimes happens with plated wheels over a period of time due to moisture trapped in that area. This may cause air to escape from the tire. A friend of mine had this happen with an Escalade. Replaced 3 wheels under warrenty over five years.

 

From the symptoms you describe, I have heard of a rare but documented problem with aluminum wheel porosity. The way that the aluminum was cast & cooled for the wheels there are micro fissures that interconnect between the pressurized interior & the adjacent exterior of the wheel, leading to the exact symptoms you are having. The 2 solutions for it are to use an acrylic polyurethane sealant on the inside of the wheel(s) & then use a larger molecular gas like Nitrogen to pressurize the tires with instead of common compressed air.