Tire goes flat when loaded, holds air otherwise

[Mountndream]

Thursday night, headed out when my TPMS starts yelling at me. Shows 71 PSI and 23 miles ago it was at 80. by the time i pull of the highway, it was down to 65.


Changed tire at a nice gas station and since it was also a truck stop, had high pressure air available so I topped off spare and added air to the tire I had taken off.


so by sunday, no air had leaked from the "flat" tire. and Autotire called and said there was nothing wrong with the tire. Any ideas?


also, the tires are new Carlise HDs, just got them this May, have about 5k miles on them. Always run at 80 PSI on a 9k 5th wheel

[JohnD10]

Possibly a bad valve stem or microscopic cracks in the wheel?

[Paulie1138]

Agree, maybe the valve seal did not seal all the way after your last inflation/pressure check? Put it back on, drive it around a bit when it is easy to do, see how it holds up.

May have even been a rim seal leak that resealed itself...or as JohnD10 says, rim issues that show up under a load?

[wmtire]

I have also seen valve cores stick, or get bent by a person checking the air pressure.

This can allow air to bleed out, then sometimes the core closes up a second time or when you check pressure again.

We once had one of the oil/change lube places near us, that had an air chuck that was messing up the cores. After we replaced a lot of them, we were able to find out the common denominator, and I went down a looked at their air chuck, to see the problem. They replaced it and problem was solved.

[Mountndream]

since i have the non flow through TPMS sensors, i haven't added/ needed air since June or so.

[RickV]

Originally Posted by Mountndream

since i have the non flow through TPMS sensors, i haven't added/ needed air since June or so.

Check your valve stems I have had problems with the rubber base ones cracking. I don't notice it until I go to put air in em. They hold air when stationary. I have a TireTraker TPMS system and I think the movement of the sensors while driving is causing the problem. Just got back from a nightmare trip where I had 3 blowouts. I ordered all metal valve stems yesterday.

[doc73]

We had a small defect in a rim (turned out to be two later this season) that would leak air when the rim warned up. Once it cooled the hole sealed up and held air.

[youroo]

We had a DIC alert of a low tire on TV. Dropped trailer and went to "Michelin Tire "as that is what the tires are! They removed the tire and checked it??,said Not our problem! We went to Chevrolet Dealer and they replaced the valve stem N/C and we were on our way! Sorry Tire Dealer! Youroo! !

[Thurman]

Another vote for the valve stem being the problem. I had a tire go flat in my drive way hours after checking the pressure in all the tires on my TT. I removed the tire, took it to my local friendly tire shop where they over inflated it to check for leaks and found nothing. The tire guy had a little tool in his shirt pocket that he jabbed at the valve core stem and repeatedly sprayed soapy water on the valve stem. After one of the jabs the soapy water bubbled like a bubble bath. He says the core just would not seat correctly all the time. All new heavy duty metal stems on all tires, including the spare. Not a problem since.

[DouglasReid]

Even so............It is only flat on the bottom, the rest sounds fine to me.

Sorry, I just could not resist...........

[JimMorrell]

I experienced a leak in the wheel itself. You might want to check this out.

[UT_Grandpa]

If your tire is inflated to 80 psi as a spare tire not touching the road it will be 80 psi under load and not too surprisingly the pressure on the road surface is 80 psi whether loaded or unloaded. What changes is the amount of tire making contact with the road and the amount of surface contact will be your weight divided by the inflation pressure in square inches.

I had a tire leaking air occasionally and it was a loose valve core. Tightened it up and all is OK.

[JLeising]

Originally Posted by Thurman

Another vote for the valve stem being the problem. I had a tire go flat in my drive way hours after checking the pressure in all the tires on my TT. I removed the tire, took it to my local friendly tire shop where they over inflated it to check for leaks and found nothing. The tire guy had a little tool in his shirt pocket that he jabbed at the valve core stem and repeatedly sprayed soapy water on the valve stem. After one of the jabs the soapy water bubbled like a bubble bath. He says the core just would not seat correctly all the time.

My father - a mechanic in the middle of the last century who taught high school auto mechanics in the 1960s - said “always check a valve for leaks - spit on it - before putting the valve cap on”. That advice has served me well. Tire valves often don’t seat quite right. A quick press and release usually fixes ( no bubbling spit).

[KEN9XL]

Originally Posted by Mountndream

Thursday night, headed out when my TPMS starts yelling at me. Shows 71 PSI and 23 miles ago it was at 80. by the time i pull of the highway, it was down to 65.


Changed tire at a nice gas station and since it was also a truck stop, had high pressure air available so I topped off spare and added air to the tire I had taken off.


so by sunday, no air had leaked from the "flat" tire. and Autotire called and said there was nothing wrong with the tire. Any ideas?


also, the tires are new Carlise HDs, just got them this May, have about 5k miles on them. Always run at 80 PSI on a 9k 5th wheel

Let us know what you find, I'd be curious to know.
(valve stem, rim, cold vs hot tire, etc) Thanks!

[rsdata]

sidewall pinhole...

I had a tire with a tiny pinhole leak in the sidewall... depended on where the hole in the sidewall was located when I parked, it then leaked either a lot, or very little. By very little I mean a # per 2-3 days, or a lot... like several #s overnight.

Tough to find that hole...

[pibi]

I think the tpms sensor could gotten loose allowing a small leak.

[Kaboom]

I had the same problem. Installed non flow through TPMS on rubber valve stems. Tires held set psi for month. Took a trip and one started loosing air not alot but enough to be concerned.

Long story short. When the tire was rotating at speed the weight of the TPMS would bend the rubber valve stem (centrifical force), air would leak around the stem hole in the wheel and stem. Took awhile to find this.

Most likely why the TPMS instructions suggested using metal valve stems. I have metal stems now.

[Travelin Therapists]

My guess is you have a small nail in your tire. The load is flexing the tire to allow for leakage.

[EdnKat]

Pump it to 80 psi, submerge it in a tub of water, or something to get parts of it under water. Like a splash pool a foot deep. It'll bubble.

[TNVJONES]

Keep us updated on what you discover