Tire leaking like magic

[Makalu1]

Got back from a trip mainly driving on gravel roads and found my back right tire was low. The book says it should be 62-65lb and it was down to 20. I aired it up and took the rig to Big-O where I sat for 2 1/2 hours to be told they could not find a leak. The guy said he cleaned the rim and tested it in water under pressure and saw no bubbles. I assume he got the right tire, pretty sure he did. I got out of there without a charge but pretty pissed. I let the tire sit a day and a half and it's now down to 20 pounds again.

Any thoughts? I will be taking it to another place to check it out-again.

The tire is Toyo Open Country A/T (All Terrain) 285/75R16LT 122Q.

Thanks as always,
Scott

[TomH]

Did they check the valve?

[daveb]

X2... Hopefully they checked the valve and valve stem.
I had a similar situation and when they looked closer found a fine crack in the rim. It was an American Eagle rim that came with the van.

[TomH]

Originally Posted by daveb

I had a similar situation and when they looked closer found a fine crack in the rim. It was an American Eagle rim that came with the van.

Was the wheel aluminum?

Makalu1, are your wheels Al? They are lighter, but more expensive, subject to stress fractures, and the bead seal wears faster. You can get better, and even more expensive ones with scandium added to the alloy. This is a big issue trucking lines look at when figuring what's best for their bottom line.

Some aircraft and rocket fuselages now use aluminum-lithium alloys with possibly a trace of copper and zirconium too. This is lighter, stronger, and less stress-fracture prone, but even more expensive. I'm not sure if it can be cast as a wheel; I believe it can only be welded with friction-stir welding.

Anyway, if the wheel is aluminum a micro-fracture could be possible.

[86Scotty]

Don't sweat it, just check your tire frequently for awhile and see if it comes back.

I've had this happen twice in the last year, on different cars. I recently got tires put on my car and drove it for a week or two, no problem. Then one day after sitting in the garage for a weekend it was down to about 20. I was pissed, thinking one of my new tires got a screw in it or something but I could find nothing. I aired it back up and have check it every couple days for the last month. It's dead on.

This exact thing happened to my wife's car a year or so ago.

[carringb]

My mystery leak on a rear tire was indeed caused by a cracked aluminum rim.

Also, if you have rubber valve stems, they can burp air when pushed on. I had a tire lose air in the Fiesta from parking the valve stem against a curb.

[86Scotty]

Originally Posted by carringb

My mystery leak on a rear tire was indeed caused by a cracked aluminum rim.

Also, if you have rubber valve stems, they can burp air when pushed on. I had a tire lose air in the Fiesta from parking the valve stem against a curb.

I think that's what happened in both cases on mine. Has to be.

[Makalu1]

Thanks for your input everyone. So having sworn at and sworn off Big-O, I found another local place, Victor's Tires. What do you know, they found a hole and repaired it. I suspect the Big-O folks inspected the wrong tire. Another plus for Victor's is that they've got a Mexican restaurant attached which we returned to this eve and the food was quite good. The two sides of the business have a common entrance and it's kind of funny to smell rubber one second and tamales the next.
Again, thanks for the input, I always learn more useful info here.

[larrie]

I love the smell of rubber tacos in the morning.🤣

[MadScience]

I had one of these on an ebay OEM ford rim. Two (three?) _small_ rounds of slime put an end to that. It now holds 70 PSI for months at a time.

Edit: Mine was leaking at the valve stem if you touched it. A new valve stem didn't solve it. Slime did.