tzoid9

I've got a new 2018 leftover Z06 that I've had since December, 2018, that now has 835 miles on it. I'm finding a very slow air loss in one of the rear tires....loses about 2 lb. every month. The last time I had it in the dealer's service was the 500 mile oil change and asked the mechanic to visually check the tire for a nail and afterward he told me he couldn't find anything. I'm now wondering if the wheel could be cracked. I bought this car with 2 miles on the odometer and I am positive that it has never hit a pothole...ever! Any suggestions on how I might find the problem? Thanks!

DTOM

Could be a small crack or something as simple as a loose valve stem. Or take the tire to your local tire shop and have them water dunk the tire to check for leaks.

Valve stem tools are only a buck or so at Autozone:
https://www.autozone.com/tire-repair...ool/487510_0_0

DJackman

Take it to a tire store and have them do a dip test .
My truck had a slow leak and they dipped it in the tire tank and there it was , a crack on one of the spoke

Mr. Gizmo

Which wheels do you have? Black , spectra grey, nickel or chrome on cup style of the standard issue star design?

pcguy2u

Spray some water with dish soap on the valve stem and carefully inspect for any sign of bubbles, even spray the inside where the actual valve is.

Or, pick up a valve stem tool and tighten the valve inside the stem. Believe it or not, when I had the wheels on my Z checked at the dealership, I got it back with a loose valve on one of the wheels.

Or just ask the dealer to dip the whole wheel/tire in a tub of water. That may not find the problem because the tech will be looking for a stream of bubbles. Your description suggests the amount of air escaping may be too little to be detected except by the most discerning eyes.

KCLARK

I had the a similar issue and found where the culprit was by washing the wheel with soapy water and watched the bubbles form around the stem which I had to have tightened and problem was fixed.

atljar

Ditto, just a touch of dish soap in a water spray bottle. Hose down the wheel and tire with the solution. Tire tread, tire beads inside and out, and valve stem. Watch for 1 min. The leak will show as foaming or bigger bubbles depending on the rate of leakage

X25

Are they cup 2? I've had pressure loss issues with both Cup2 tires, as well as Hoosiers, since I've started using them. I've not had such issues with PSS tires, though.

tzoid9

Thanks so far for everyone's ideas. These are Spectra Grey wheels with the standard Michelin tire, not the Cup tires. I haven't tried the soapy water spray yet, but will this weekend. I have checked the tire valve and it is tight. Any other thoughts, please keep firing them through. Once I solve the problem I will report back just in case someone else runs into a similar problem. Thanks!

Bill Dearborn

A tight valve stem can still leak. There is a rubber seal that fits the hole in the wheel and that could be where the leak is.

All of that stuff is covered under warranty so have the dealer fine the leak.

Bill

pcguy2u

Yeah but, if the leak is from a crack in the metal, GM/Chevy is going to deny a claim.

FiftyFiv3

Probably a crack, GM warrantied a cracked wheel for me.

pcguy2u

Early on GM was trying to make good on these wheels, but after so many went south they claimed that their testing of the wheels suggested that their construction was in spec. They then used the guise that the problem must originate in states that have bad road conditions.

I know the above covers a lot of ground, but the proof would be to hear from some folks who got GM to warrant a claim made recently.

FiftyFiv3

I got mine warrantied a couple of weeks ago.

pcguy2u

Crack or bent wheel? Just one?

0bbbvettes.com

What part of the world are you? I believe you can get it warrantied if you push hard enough at a local store. If you are near one of my friend's stores, I will direct you to them and they will assist you.

Truthfully, I do not believe it was you, and I believe it is most likely both of your rear wheels have a crack.

Our store and my friend's store (we both own Vettes and are both aware of the wheel issue personally) we started paying attention to how quickly a few customers were coming in for cracked wheels with air leaks on their practically brand new cars, always on their rear wheels only.

We knew that hitting a sharp bump, that is tall enough to cause the tire to leave the ground, and with enough vehicle speed to cause the tire to leave the ground, is capable of bending wheels (we have tested it on a road with a sharp bridge seam that goes all the way across the road, which literally can't be dodged)

After communicating with other stores, I found that it was a common occurrence that the stores had at least 1 customer, who swore the store's employees/customers bent the wheels test driving the vehicle prior to them purchasing it. The only problem is, the cars were never test driven. The only people who could have bent the wheels are the techs during the initial PDI process when the car is prepped and taken out of the wrapper after the car comes off the truck from the factory.

So we put our focus onto our PDI techs... maybe they were the trouble makers. But it would still require each of these PDI techs at different stores to all hit a sharp bump that causes the wheels to go airborne on their initial drive of the vehicle. None of us could find a spot where such an impact was occurring on the nearby roads that the PDI techs use on their routine short inspection drives.

So the mystery deepened.

So then the idea came to us, maybe somehow the wheels are being damaged in transport, maybe it is the straps they tie the cars down with? (I did not like this idea, it was one of my friends who proposed the idea, and I explained the cars wheels and tires experience much greater force while the vehicles are hitting normal bumps at high speeds, the straps on the trucks are not bending the wheels imo)

But just to pacify my friends, we started to check if the cars had bent wheels as soon as they came off the transport truck.

We put the car on a lift, and give the wheels a spin while the car was in the air, while still in the transport white wrapper, and eyeball the inside lip of the wheel, because when they are bent, it is obvious and the inside lip goes up and down instead of stays in one spot and runs smooth.

Sure enough, not all of, or not most of, but a few corvettes have been discovered with bent rear wheels... right off the transport truck while still in their wrappers. So my friend who discovered it first, became furious, and they escalated it, and GM fought them on it, but eventually my friend won and GM put new wheels on the new car. We have started to document this, because let's face it, its a headache for our dealers to have to mess with this problem. Customers perceive us as the badguys, when in all actuality, we wish GM would solve the problem to keep the customers happy, and we don't want the brain damage of the furious customers and having to fight GM to get wheels fixed for those furious customers.

Another friend of mine who spent a lot of time here, came across an interesting video discovered by another member. He brought it to my attention instantly, as it was/is the piece of the puzzle I believe we are looking for.

Go to the 17 minute mark, watch the last part of the video until the end.

Tires and wheels hitting a tall sharply focused bump, so hard that they become airborne, even when the car's suspension is trying to keep them planted against the ground.

Now, do we know this is what is bending the wheels? No. But do we know that sometimes wheels are being bent before they ever arrive at our dealerships? Yes.

And this video is the only logical way I could see it happening unless there is a test track/road with a sharp bump that at least some of the cars are driven on prior to being loaded onto the transport trucks to our stores.

So the last question one may ask is "why does it happen on only a few Vettes, and not all others?"

I believe it is a combination answer between the speed the bump is hit by the driver, and also the inconsistency in wheel batch strengths.

I do believe the forum members who swear they have never had a wheel issue. Many first year 2015's had stronger wheels we believe. However, we believe the quality control on the wheels deteriorated at later dates as GM started to subcontract wheel production to other suppliers in other countries.

I apologize for the long story, I am simply trying to give you the confidence that you need, to pursue this problem and pursue new wheels under warranty, should yours indeed be cracked as I predict they will be, and I hope this gives you the confidence to escalate the problem as needed, and if you have not hit a sharp bump that you believe caused all of your wheels to hop, and thus you do not believe that you were the one who bent your wheels, then I am not doubting that you are in fact telling the truth.

And thus, you should not have to shell out $1,500 dollars for something that was not your fault.

The bump does not have to be hit fast, it just has to be a sharply focused impact point (like a bar) which is enough to cause the wheels to hop 4 or more inches off the ground.

I wish we would have been checking for this a couple of years ago, when we were selling more Corvettes, but due to slower sales now, and lack of new orders, my personal store does not have enough cars coming through to check enough cars to document patterns, but I have spoken with some of the larger stores, and moving forward they are documenting this problem when it occurs... and it is occurring.

Our goal is to make sure that moving forward, customers have the option to elect for a fully forged wheel. We are putting together our findings and providing them to GM.

I also write this post, to encourage other dealers to check for this problem using the lift and wheel spin method mentioned above. There is no need for conducting time and labor-intensive processes of dismounting of wheels to put on the road-force balance machine to see if they are out of round. Instead, just give the wheels a spin while you are under the new cars, and video the inner wheel lip wobbling up and down if it does, while the car is still in the wrapper. Then if you want to further document the problem should you discover what looks to be a bent wheel, throw those wheels and tires on the road force balance machine and get an actual data readout for documentation, and submit it all to GM, and contact me to let me know that you have submitted it and on what date it was submitted.

Thank you.

Carvin

What are they doing in that video, a suspension test?

Bought my Z used. Dealer replaced a cracked rear found prior to purchase. So I don't know how the Crack got there but I've been okay from that point on.

0bbbvettes.com

I know a set of flat train tracks which I can go across, which don't seem that rough, they are on a 45mph road, but if I go across them quickly, at say 30mph or so, I will have a bent wheel afterward almost every time. I don't feel the tires hopping per se, but I feel the vibration in the bent wheel instantly after. I have 8 wheels which have been bent and/or cracked, and I have 2 bent wheels on my Corvette as we speak which takes my tally to 10 on this car, and I try not to bend them because its a headache, even for us dealer owners dealing with the insurance companies.

But when I watch the video, the back wheel hops, and I believe it is actually the second bar that does the damage as it comes down and hits, the wheel then has to then change directions and go back up again, if this overall station/location is in fact where it is occurring.

At first, I believed there is no way the cars could be going fast enough to bend their wheels at this station exiting the factory, but then I realized, its probably bumpier and more severe in focus points on the tire/wheel than the train track crossing that I know that I must slow down for as I cross.

I believe ultimately, for them to be bent before arriving at a dealer, it also comes down the batch quality of the wheels needing to be of lesser quality than normal. I am not sure all the particulars, I just know it is somehow happening.

tzoid9

Bill Dearborn & others....
Thanks very much for your potential diagnosis, it sure sounds possible. I bought the car through Crisswell's in Maryland and I live in PA. The local dealer in my town is OK, but I'm not sure I can trust them not to scratch up the wheels and/or lug nuts while trying to solve this problem. Believe me, this car has 867 miles on it right now and it is flawless, better than it was when I had it delivered to my home. It's never been driven in the rain or any foul weather and it's never hit a speed bump or pot hole of ANY kind.
The car has been professionally PPF'd with Xpel Ultimate and professionally paint corrected and Ceramic coated. I get concerned about just anybody touching this car. I'm going to try the soap trick this weekend and hope I find something. I hope all those thoughts that a wheel being cracked are wrong, I wouldn't be excited about an argument or fight with GM about a warranty claim, but I will if I have to.
Thanks to all!

tzoid9

....and Bill Dearborn, sorry I took so long to respond. Apparently my response to you got rolled into an old thread on a similar subject and someone was "kind enough" to let me know the error of my ways....and I suitably responded back to him......
What a surprise when I read your sweet note you left me....I am so ashamed! Regardless of the fact that I didn't know this cardinal rule, I find it somewhat simple minded that anyone (especially me!) would go to a thread as old as the one you reference (it's over 10 years old by your count) and respond to it. If you look a little closer, quick draw, you will see my original thread here and I'm surprised you didn't already see it ...

"https://www.corvetteforum.com/forums/c7-z06-discussion/4284347-slow-tire-leak-on-new-z06.html".

One of the Forum members, Bill Dearborn had responded to my thread, which started just one week ago and I intended on responding a "thanks" back to him. Apparently in my haste, I didn't notice that the system hooked me into the next closest related thread, which was this 10+ year old piece (I apparently drove thru my own thread) and I answered Bill Dearborn there. I apologize to Bill for my error and thank you for pointing out so vividly my obvious mistake. Thank you for your attention in this matter.