I've got a front left tire that's been driving me crazy all winter. It will hold the proper pressure 30 fine in my garage for months but then when I take it out in winter for a run, it will lose 5 lbs on the highway within 5 miles. I pump it up again with my compressor and it will run
fine in town but slowly leak air again but not as quick as on the hway.
It's a 99 with the orig. sensors (they still work and are still accurate
as I check the tires manually as well). The tires, wheels, and hardware
on the sensors are all almost new (less than 3000 miles).

It can't be the tire as it holds air fine in my garage. Not so sure on the tire valve. What would cause the pressure drop when driving on the hway more than around town? I'm hoping it's not the wheel somehow...
it's a chrome repro Z06 motorsport. Can't do much now with the snow
in Jersey but before I take it in, any thoughts?

Jerry

 

Cold air lowers tire pressure and as the tires heat up the air pressure raises. If you fill your tires with nitrogen instead of air the pressure will stay constant regardless of temperature. Most tire shops have nitrogen now, it will also make your tires last longer and help with fuel mileage.

 

I'm not convinced about the advantages of nitrogen in tires. I agree driving causes the pressure to rise, that's what my other 3 tires do but not this front tire. It doesn't rise at
all, just drops in pressure in winter especially at hway speeds. Plan to take a run tomorrow, it should be around 40 in NJ. May have to have a shop take a look at it.

Jerry

 

Check that tire for foreign objects. Often when screws and nails are in a tire, it will not leak if it sits correctly, but driving it or if it sits on object, it will lose pressure.

Nitrogen is not "ALL THAT", mainly it is the lack of moisture that accounts for more even pressures, dry air will do the same. Nitrogen molecules are larger that oxygen and will not leak out of a tire (through sidewalls not a hole) as fast.

 

I have an O seal on the TPS which needs replacing. It leaks slowly over a week. Not sure why it would be OK not driving but leak on the move though. If it is the o seal you can tighten the nut but it'll need replacing. I plan to pop a new TPS in when I change my tires

 

Well, I finally solved my slow leak...

Sunday in Jersey was pretty warm almost 50, so I took the C5 for a spin. Same story,
start off fine at 30 psi, lose 5 lbs in 5 miles of hway driving, pump it up back to 30, fine
in the city and in my garage. Take it into Sears and they conclude tire is ok but the small inner removable valve of the sensor assembly is causing the leak but they don't have the tool to remove it and suggest I take it back to the dealer.

Take it to a local tire shop yesterday, go thru the whole story and he scratches his head,
takes his tool out and replaces the valve in 5 seconds. Tire has been fine ever since.

Both Sears and the local tire shop did not charge me a dime, how's that for for a reverse
Corvette tax, maybe they were thrilled to see a C5 driving around in winter NJ.

Here's the moral of the story. I have chrome Z06 Motorsport wheels, professionally installed with new hardware but I did not order in advance the chrome hardware so instead I've been using some cheap chrome caps and valve stem covers from KMart.
Apparently, one of the valve stems was sitting up too high and the cap/covers bent
it, thus the slow leak on the highway. I suspected same and was even running the
valve w/o the cap but I never knew about the bent valve, never knew they were removable with the tire on the car. So, if you order new chrome wheels, order the chrome hardware
to match or just make sure you don't have this problem. It's been bugging me all winter.

Jerry

 

Glad you got it solved. Something like that would drive me too.