Tire Pressure Loss Issue at Higher Speeds

[Jacob]

On my first road trip at higher speeds, I discovered a strange issue on a 2007 Z06 front Goodyear run flat (mileage about 3500 miles). At speeds below 60 mph, all is normal. Above 60, I start to experience pressure loss. The higher the speed, the faster the pressure loss (up to a rate of about 1 psi per 2 miles). We have verified the tire pressure sensor readings against a manual tire gauge and it is fine. We have checked tire tread and bead with special soap for leaks, at 30 and 45 psi with none found. The factory wheel has been checked with special soap for leaks and none found. Upon removal and inspection of the tire, the dealer has noticed "crowns and valleys" on the inside of the tire opposite the tread side. Almost seems like inner tire belt has delaminated very slightly. Dealer has looked at another brand new GoodYear run flat off a CTS-V and found no similar crowns or valleys inside. Dealer has ordered a replacement tire for the Z06 front and will compare the new tire with my tire, looking for crowns and valleys (or the lack of). If no crowns are found, he will change out the tire under warranty.

Just wondered if anyone else had experienced this problem.

Jacob

[itsaz]

I have a similar pressure loss at higher speeds but believe it's due to the grommett on the pressure sensor. When I had the tires replaced, the tire changer hit the sensor with a tire tool. When the tire was inflated it held pressure just fine. On the way home, I began losing pressure as you describe and noticed the nut holding the sensor to the wheel was loose. After tightening the nut, pressure held fine until the next time I had the opportunity to make some high speed blasts. Had to tighten the nut again and all is well. I believe the grommett got crushed and loosens up over time. I plan on replacing the $3.50 grommett before I get too concerned about the tire.

[c4c5specialist]

HI there,
Many grommets have been found to cause pressure loss, as temperture of the tires and internal pressures increase on the rim.
It would be suggested to have them check this first.
Its good to hear that your dealership is being proactive.
Please keep us posted, c4c5

[Jacob]

Thanks for your input. I checked all 4 corners and found the nuts to be well under the required 62 inch pounds torque. This would not explain why only one tire lost pressure, but we should know more after the tire comparison is done.

[Jacob]

Dealer got new tire in stock and after inspecting the inside, detirmined that it was different from my problem tire. The new tire did not have pronouced crowns and valleys inside. Dealer replaced my problem tire with new tire under warranty. He will not close the work order until I report back to him after a suitable road test.

I have to say this dealer went the distance on this problem.

Jacob

[b beep]

2007 coupe, monterey red, paddle shifter, no mods. I have several digital tire gauges that have always been reliable and have been checked at a local tire shop and found to be accurate. When I check the cold pressure with the digital gauge I have a consistent 30 lbs. Start the car and the DIC shows 28 lbs. in all tires. I spoke with a service tech at my dealer and he informs me that it is not possible to correct the readings from the tire sensors. I’ve read enough on this and other sites to know that the service techs answer may or may not be correct. Any additional information on whether or not the sensors can be changed to reflect the actual pressure would be appreciated.

This somewhat minor tire sensor problem and a bad battery have been my only complaints. Car is just about perfect in all respects and is light years ahead of my 99.

[c4c5specialist]

HI there,
Tolerance is plus or minus 2 psi.
However, pencil and digital aside, the calculations take into account barometric pressure from the outside, along with the sensor readings.
You are normal and no repairs are necessary.
Allthebest,c4c5