I running into a bit of a strange tire problem. I recently had the tires replaced on my 17" wheels. I ordered the tires online and had them installed by a local garage. Ever since then, I have been having what appears to be an intermittent leak from my left front tire. I'd typically fill the tire to 42psi in the morning and, by the next morning, discover it to be around 34-35psi. My commute each day is approximately 100 miles round-trip. This is very repeatable. I have been back to the mechanic. He removed the wheel and very carefully examined the valve stem, rim-tire bead, sidewalls, and treads for any leaking using the soapy water method. We couldn't find anything. The only other clue I have is a trip I took last week. I drove about 240 miles one day. This time I discovered the pressure dropped all the way to 22 psi by the end of the day (surprised the TPMS didn't come on). This leads me to believe the leak only occurs while driving, explaining while we couldn't see anything under static observation. Has anyone ever experienced something like this? I'm thinking maybe something is wrong with the seal and the centrifugal force while driving is just enough to release some air.
I had this problem some years ago on an MGB V8 it turned out to be a nail in the tread (headless type nail) that only leaked when weight was put on the nail at an angle that is as it hit the ground while driving or if parked with the nail on the road. It did not show a leak when submerged in water.
Technically speaking, there could be two issues with a "valve stem." First off, the valve core itself could be loose. It is easily tightened with a $2 valve core tool: http://hostedmedia.reimanpub.com/TFH/Step-By-Step/FH07MAY_LEAVAL_01.JPG Secondly, it could be the stem itself if it is "rubber." Hobbit had a big expose on this a few years back; bad rubber cracking. (For this reason, when I had snow tires mounted on an extra set of rims, I specified stainless steel stems like the OEM ones that came with the car. (Connected to the OEM TPMS sensors.) On older cars, small pressure losses can result from rust/corrosion between the rim and tire bead. But its hard to see how a stem or bead related problem would result in tire pressure loss only when the car is moving. I'm of like mind with Britprius; the pressure loss is most likely from something small and hard to see/find like a nail with its head worn off, etc.
Very hard to believe I picked up a nail within the first couple of miles after getting the tire installed. Also, examined the tread very carefully. I'll check again if the new velvet stem doesn't work.
It seems like a solid example of O'Toole's Corollary of Finagle's Corrolary to Murphy's Law: "The perversity of the Universe tends towards a maximum"... Which is related to the belief that, "Inanimate objects are out to get us," also known as Resistentialism. Finagle's law - Wikipedia
Well, the mechanic who installed the tire sent my car over to a tire/wheel specialist who re-beaded the tire. I will know by tomorrow if this fixed the problem.
