Mhelvic

I searched the forum for this very issue and found several solutions, but they have not worked for me. My Dilemma: The wife and I recently took a trip; about 400 miles each way and I checked the tire pressure before leaving to make sure all tires were 30 PSI cold. After hitting the interstate I was averaging about 80 mph while driving and then 2 hours into the drive I get a low tire pressure warning for my LF tire.

The tire pressure dropped to 23 PSI while the others were constant at around 34/35 PSI. I stopped, checked the tire found no nails, screws or punctures and inflated the tire to 35 PSI and then continued on. As I drove I kept watching the TPMS for that tire and it would drop 1 PSI about every 15 minutes so I tried varying my speed between 70 & 80 mph, but it still dropped at that rate and I had to stop about every 2 hours to re-inflate.

When we got to our destination it was late at night so I re-inflated the tire again and checked into the hotel. The next morning there was no loss of pressure, but I took it to a tire center and had them pressure check the tire, check the valve stem, and they even submerged it under water looking for leaks -- nothing.

We drove around the destination city at normal city traffic speeds (not exceeding 60 mph) for several days with no loss of tire pressure. But on the return trip home we had the loss of PSI and stopped every 2 hrs to re-inflate.

Got back home, checked the forum and found similar issues with the torque spec of the valve stem and the TPMS o-ring seal being possible culprits. Took vette to the Chevy dealer and had both those items checked as well as having tire pressure tested afterwards. Was told everything checked out. I hit the interstate again for a 30 minute drive and its still losing 1 PSI about every 15 minutes.

Thanks in advance and sorry for the long post, but any ideas about a fix would be appreciated. Also, the vette sitting in the garage for a few days or normal driving around town still no loss of PSI.

ChevyDave

wow.. that's a good one. your no loss in city driving sorta kills all my ideas. Yet there are only 4 ways to lose air, tire puncture, tire bead , value stem (internal and outer seal) , and cracked/damaged rim.

i'm betting on my number 2 guess below
ok, so...

1) thinking back, Click N Clack had that as a puzzler i think. but they said valve stem, you ruled that out. still i would put some soapy water around/on it, manualy flex it to see if it bubbles

2) second would be small nail with no head like finishing nail, that would hide almost invisible, but ooze only when rolling caused by the flex of the bending rubber around it.

3) third would be the bead, again flexing as the rim went around, but if the tires have been on for a long time, sorta rules that out.

hummm.. i suspect your going to end up having someone pop the tire, reaching in and feeling for a poke of a nail , failing that , treat the bead and rebead it (also checking rim for crud causing a bad bead) , also a new stem kit rubber washer just in case.

i cant tell the year of your car, but if the tire sensors are getting toward 5+ years, might as well put new sensor in if they unbead it.

Mhelvic

Sorry it's a 2007 with OEM rims and tires. I'm the 2nd owner, bought it in December 2012 and it had 9000 miles on the odometer. It has 12,000 miles on it now and the rim has now scuffs, scrapes or other signs of hard wear and the tires have about 90% tread left. Other then the drive home from the dealer this was the first it was driven on the interstate.

Don-Vette

Did you check the pressure with an actual gauge or just relying on the TPMS?

obxchartercaptain

..You could be getting faulty readings from that one sender.

wera32

I think I would replace the O ring on the valve stem/tpms. Either that or the stem/core is leaking under centrufugal force. Checking it static isn't working so a little parts replacement is going to be required I think. In fact for the low cost of the tpms I'd probably just replace the whole assembly or even the set as Dave suggested.

69L68

I had an intermitent leak and it ended up being a crack in the wheel that would leak under torque.

Steve[/I]

AORoads

I would think the tech would've checked the pressure with an actual gauge (as might you have at least once, not just the DIC readout), but maybe not.

Of most suggestions above, I'd guess the nut, the TPMS itself (needing replacement), or a nail/screw that's not visible. These TPMSs are supposed to last 10 years or more, but if your car's an '07 it could've been produced in mid '06---that puts it at about 7 years old now potentially. Wera's post has some potential issues, too.

BTW, does it leak at all if you leave it in the garage overnight?

weathermaker

If your adding air, then it's leaking out. As suggested, I'd start with the O ring and valve core first. I heard of people having a problem with corrosion on the rim at the bead lip. Tire would have to come off to check. If the rim is cracked you could try some kind of food coloring in the tire and see where it shows up. (this is a stretch I know)

truckplay

check the bead area. outside of a puncture or slit, you may have a problem with the wheel.

EtidW

cclive

I'm betting on a nail or some sharp object that can't be seen. It is not uncommon to have a nail that is well sealed and only leaks when the tire is flexed, with more flexing at higher speeds. If it were mine, I would just have a tire store take the tire off the wheel and inspect the inside. For $16 it would at best find the leak and at worst rule out a puncture as the cause, all for a reasonable price. They should mark the position of the tire on the rim so that no rebalance is necessary. I got my Michelins at Costco so that is where mine would go.

4thC4at60

I had an intermittent leak, turned out to be the nut wasn't tight enough on the TPMS.... tightened it, no problems since - 10,000+ miles...

bucwheat

Every once in a while I get the service RF monitor,I check the pressure and it right were it supposed to be.

MikeERWNC

I had this when I bought my 2007.

First, I sprayed the tire with soapy water as my wife rolled to car in a tight circle.
No leaks.
Second, I replaced the shrader valve in the front right.
That didn't do it.
Third, I replaced the valve cap with a steel cap and new o-ring seal.
Nope.
Lastly, I pulled the wheel. aired up the tire to 50psi.
Sprayed soapy water EVERYWHERE. I went through a gallon and had to wipe it from the garage floor.
I was going to replace the tire.
I dropped the pressure back to 31psi.
It never leaked again.
My thought is that the higher pressure actually seated the tire 100% on the bead.

Also, I change a lot of motorcycle tires.
I have had people complain about loosing air from night to the next morning after having new tires installed.
If the bead on and aluminum wheel has any corrosion, air will escape out.

My test for you would be to pull your wheel and let all the air out.
Spray the bead on both sides with soapy water so it will soak down into the bead.
Then air your tire up to 50psi, let it sit for a few minutes and drop it back down to 30psi and see if it stops leaking.

bucwheat

Goog point,never thought about the tire not fully seated.

1bdvet

Funny thing I get same on left front tire, and pressure is right on the money.
Must be those gremlins.

MikeERWNC

Some places will air up the tire until the second bead pop then stop, put the valve in and then air it up to the correct PSI.

I have only been changing MC tires for about 35 years, I always go to about 50psi, then install the valve and take it back up to the correct PSI.

I have not had a tire leak out like my Vette was doing.

I hope this works for him.
I hate dealing with tire shops.

CaryBob

I have had nails that were essentially invisible until the tire was taken off the wheel. The tires lost air very slowly at rest at 30psi but very rapidly on the highway at 34/35psi. Might be worth taking the tire off the wheel and feeling the inside for a nail or screew.

Mhelvic

Yeah, each time it lost pressure it checked it with a tire pressure gauge and it was spot on with what the TPMS displayed.