Kimo-C6

I hope get some light on this perplexing issue with gradual air leak from one of my tires…I know what you’re thinking, what’s so perplexing about an air loss on the tire…well, let me explain.

Day 1,
On my way to work early in the morning and on the freeway I get a message on my dash; “LT Rear Tire Pressure Low” I push the info button and sure enough it shows 23PSI. I immediately suspect that I’ve picked-up a nail or some sort.
After work, I drove straight to the tire shop to have it looked at. The tire technician removes the tire and carefully inspects the tire for nail or any signs of tire puncture; none. Then the technician conducts under water leak test; none. No leak detected. The technician re-installs the tire and checks all 4 tires for proper inflation and pressure. All 4 tires read 35 PSI. Cool, I’m headed home.

Day 2,
I get in my car to go to work, and I get another dash warning, letting me know that the same rear left tire air pressure is low. The pressure reading is same as the day before; 23 PSI. I stop at the gas station and inflate the tire to 35 PSI. Now, this is where it gets really weird. I wanted to monitor the tire pressure on my way to work to see exactly what was going on. I scroll through the tire pressure monitor on the dash for “LT Rear 35 PSI/RT Rear 35 PSI”

Regular driving on the road; no changes in pressure, however, once I got on the freeway and at 70-75 MPH speed I begin to notice the tire pressure dropping slowly one increment at a time. The faster I drove the faster the air pressure seem to drop. By the time I arrived at work, the tire pressure read 23 PSI. So, drop of 12 PSI from 35 PSI.
My guess is either the tire bead is NOT seated properly or it’s the TPM that is all out of whack.

Folks, now you have my long winded story (Sorry). I know there are many expert and knowledgeable corvette owners out there. So, if you can assist me in any way will be greatly appreciated.

florida john

How many reasons can there be for losing air? The tire, the tire/rim seal, the stem/valve or the wheel itself are the potential reasons, correct?

Check out and replace the stem and valve if that tire comes off again.

I've had tire dealers tell me that my aluminum wheels were porous when one of my Michelin's kept losing air. He didn't care that they prior tire didn't lose pressure on the same wheel.

hawkandersonjr

Had a similar problem bought a new set of firestone wide oval non-run flat and the front passenger side kept losing air. Had it checked, resealed, and it didn’t fix the problem. Went to auto zone got a can of tire fix no more air leak.

Knob Jockey

Since you've already checked for nails/etc., the next thing to check is to make sure the valve stem nut is tightened down.

Don't over do it, you can damage the seal. Test one of the other stem nuts to get a feel for the proper torque.

Don-Vette

Sounds like a bad TPM in that tire to me.

AORoads

I would say this is the most likely case above, and what I would try first. As said, be careful NOT to over-tighten.

I would definitely NOT do what hawk did above; it is a temporary fix that could lose air at any time, and possibly quicker than a slow leak. Fix the tire's air loss--not a stop-gap fix for long term use.

All the potential reasons are pretty well outlined above as to the why's. There is a remote possibility that you have a bent rim which could have been done without a arm twisting whack.

There is also the possibility that the sending unit itself is going out (how old is the car and are these the orig. TPMS?), but if you check the tire with a hand-held gauge, that should eliminate whether it's the sensor, or the tire itself. Have you done that, or did you rely on the DIC to tell you what the tire pressure was?

I have had a bead/tire leak long ago, and it took recurring occasional re-gluing of the tire to the rim---but that was ancient history.

truckplay

do you have chrome wheels ? they do leak at the bead sometimes. outside of a puncture, torn bead area, loose or bad seal on tpms sensor, cracked rim ??? sometimes it takes a while to find. you are going to have to remove the wheel, spray the wheel & tire down with soap (so you can see it bubble) & look for leaks.

good luck

FortMorganAl

You can eliminate one of those by simply measuring the tire pressure with a hand held gauge and comparing it to the DIC reading.

If you really are losing air, which is probable since the tire tech went to a lot of unneeded work otherwise, and it is speed related then it is very likely either bead related OR a very small puncture. I've seen nails that were small diameter and worn down to the point you almost need a magnifying glass. And they won't show up with soap and water if they have a tight seal except when stressed. But they do show up as a small spot on the tire if you look close enough and dig around all the other spots that are normal until you find it. The easy way to find it, however, is to dismount the tire and look inside. That could also solve the bead issue if you still find nothing.

vig1116

Sorry for the stupidity, but is it ACTUALLY losing air, or is the TPMS just saying it is? And if it is losing air, is it losing the same amount the TPMS is saying it is low by?

paul 56

THE EXACT SAME THING HAPPENED TO ME!!! AND HERE IS YOUR ANSWER:

Your valve stem is loose. At high speeds the centrifugal force pulls the TPMS unit away from the wheel and allows air to leak out. Tighten the valve stem, and the air will stay in.

z51vett

Here is one for the books had similiar problem no one found the problem. One day I'm at tire shop see older fellow who has worked on my car before mention it to him. He takes the wheel of water test then pulls tire off wheel and feels around on the inside and could barely feel a small bump or something he marks spot goes to out side on tire and drills in it is a very small diameter nail. It was so small no one saw it in the tire.
z51vett
Doug

not08crmanymore

Make sure the nut around the valve stem is tight and no i did not read all the responses.

42Chevy

The sensor nut torques to 35 inch pounds. If you over tighten it, it will break.

42Chevy

As said above, if the tire is actually leaking and not a sensor malfunction, you have a good sized leak. For it to lose 12lbs in a day it should be easy to find. My guess is the tech just missed it. More than likely a small hole in the sidewall that opens up with the weight of the vehicle. You can check it yoursel by mixiing up some car wash soap in a spraybottle and spraying down the tire while it is still on the car. The weight will magnify things and you should be able to detect the source.

txsugar08

I had the same problem on my 07. Since it was not a DD, it took about two weeks to go totally flat. Took it to my local Discount Tire and they rebuilt my TPM...all good.

John Harry

I thought it was 62 in. lbs. No?

ruxvette

42Chevy

You are 100% correct. It is indeed 62 in lbs. There goes my memory...wonder what will be next?

CMY SIX

the biggest mystery is why you didn't go to a tire shop and have then reseat the tire and put a new o-ring on the valve stem instead of posting this.

Kimo-C6

YES!
The culprit for the slow leak on my LT Rear tire WAS the loose valve stem. I checked the remaining valve stems and they were all tight, except for that one.

About a month ago I purchased a gloss black cup style wheels. I’m thinking when the tire technician R&R my tires to the new wheels he forgot to properly torque my LT Rear valve stem.

I want to thank everyone who responded. You can resolve any problems when brilliant minds come together and share their knowledge.