jbxea1

I am running Hoosier R6s (235/35/19 F, 315/30/19 R) on GMG 19" rims on my 2010 GT3. Three of the tires will not hold air more than 30-45 minutes. During a recent track session, they would lose 4 pounds every 15 laps. I had a similar problem with R6s mounted to my OEM wheels, but not as severe, as they would not lose air until the car sat overnight. My dealer is investigating the issue, but so far has not been able to determine the cause. Any suggestions as to the potential cause or a potential soultion would be greatly appreciated.

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2010 Black GT3
2008 Silverstone M5

TRAKCAR

Something is wrong. Valve stems?
Should not lose any air at all.

rlips

I am running the same sizes on oz wheels and have been working through the same issues. We found two causes:

1). The tpms valve stems were coming loose in some cases. If you have tpms sensors installed on your track wheels, you need to periodically tighten. Sometimes the stems will not re-seal when you tighten them, in that case beru (sensor manufacturer) makes a re-install kit that replaces the crush gasket and screw. You can get the kit at tire rack for 6.95 or so.

2) My tires tend to move on the rim, breaking the bead and sometimes generating little bits of rubber on the rim that prevented re-sealing. We cleaned up the rim and mounted the tires using hairspray. (apparently an old drag racers trick). This helped, but did not eliminate movement. The less movement I get, the less likely the tires seem to leak.

Make sure you mark the location of the valve stem on the tire and monitor for tire movement, I see this more on the rear tires.


Hope this helps

brim

I had the same issue at the track a few weeks back. My valve stems were loose. Tightened them up and was back in business.

On Pole

Put the wheel/tire in a tub of water and trace the bubbles.

996FLT6

My Hoosiers always lose air. If CCW it's right rear and if CW it's left rear. Go figure. My tire stems are fine. Mike

jbxea1

Thanks for the information, I will definitely check the valve stems (TPMS installed) and clean up the rims before remounting. May have to get the re-install kit for the sensors. Dealer is going to dunk the wheels in water tank to test for source of leak. I have marked the tires at the valve stem and they definitely rotate on the rim (12 to 15 inches). However, my MPS Cups also rotate on the rim and seem to hold air well. Also, my friend has an identical setup and has the same problem, but not quite as severe (tires flat by morning).

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2010 Black GT3
2008 Silverstone M5

daedton

rlips,

To prevent the tires from moving on the rim, it was recommended to get a 1 inch wide strip bead blasted on the inside of the rim on each sided where the rubber touches so that the tires have a "grippy" surface to bite on under hard braking. With R6's and PCCB's my tires were rotating. Not anymore...at all. This did the trick.

11 RS
07 RS
98 C2S
97 C4S
77 911S

TRAKCAR

Even with 3 piece BBS (I think they come with that bead blasted strip) the only leaks I have had was the valve stem. They still rotate on the rim, even with Toyo's with the stickier Hooters it was even worse.