This weekend I put the Hoosiers onto the M3, in preparation for taking it to the dyno on Tuesday to do a power-to-weight detune so that it'll be legal for NASA TT4 (was recommended to me to do the dyno tune using the same tire it will have on for the event). I haven't run Hoosiers on it before because I was previously just doing track days with NT01s. So this is a new set of wheels and a new tire (Apex 18x9.5s w/ 245 R7s). After putting it back on the ground I went around adjusting the tire pressures and on the 4th wheel when I put the gauge onto the valve stem it went BOOM and shot the valve stem across the garage. The tire immediately went flat of course.
So first off I'm really glad this happened in the garage with the car stopped, not loaded up in a corner at 100 mph. Second though -- WTF happened? Defective valve stem? Could it have been incorrectly installed? Everything was new and unused (wheel, tire, valve stem), and I had them mounted at the same shop that does all my tires. I haven't found the valve stem yet.
I'm gonna call the tire store tomorrow about fixing that wheel, but now I'm a bit spooked. The valve stems on the other three tires are visually different from the ones on the other wheels I've gotten mounted there (like the NT01s), so maybe it's a new manufacturer they're using? Do valve stems come in different sizes, or are they all the same? I put on some safety glasses and peered at the other three stems and they all look normal, but...
Look ma, no valve stem!
I'd guess they tore it on install. I, too, would Feel uneasy about the others but give them a good push and pull and if they hold and don't show signs of damage, you'll probably be ok.
That sounds not great.
I have a new set of 949 racing metal stems that I've been meaning to install next time I change tires but that won't be for a while - you're welcome to them if you want to come up here and grab them tomorrow.
Can you post a picture of the valve stem? Some rims like BBS use a specialty stem that has a threaded nut on the back, maybe it came unthreaded. I always liked the regular old tapered rubber ones, pretty hard to mess those up unless they physically tear.
That is quite unusual.
I changed tires at my grandpa's shop from age 13 to 17. And worked there until age 24.
I never saw or heard of a valve popping out of a wheel before.
I remember some crusty old rubber valves that I could break off with my hand to let the air out but were still holding air when the customer got to the shop for new tires. We almost always had to cut off the base with a knife to get the old valve out.
I have had that happen one in 25 years in the automotive service industry and that wheel and tire was a 25 year old combo that was being replaced. The stem and tire were both rotted and the stem blew out whole. I've never seen a new one fail in that manner.
I took it back to the tire store this morning, they found the entire valve stem inside the tire, in one piece. Looks like I was wrong about it blowing out -- I thought I saw something go flying across the garage but it must have been an illusion. That explains why I couldn't find the valve stem on the floor, at least. :)
So it seems like the tech just didn't pull the valve stem into the wheel hard enough and when I pressed on it with the gauge the air escaping around the seal pulled the valve stem inside. That makes me feel a bit better, I was worried about defective valve stems and what that might imply about the other three.
That's exciting. Glad it worked out as well as it did!
