No. A cap off a valve stem will not cause a flat tire. There it a shredder valve inside it. It will only let air out if someone pushes it with a small object or takes it out unless it is not all the way in there or is a problem with the seal. most likely while you were driving it picked up a nail or the bead is leaking also the valve its self could be cracked and leaking there. the last thing I have seen is a cracked rim or rusted to where it leaks from the rim but that is rare and I mean rare

Just an FYI, you can tell a flat tire before you cause damage as your steering changes.

I'd suggest after getting this fixed, that you do some VERY short drives (few hundred feet at most) with tire pressure in one tire around 10PSI. Where the steering wheel sits in relation to "normal" (which is why it's important that the steering wheel is centered when driving straight under normal circumstances) will tell you something is wrong with the tires or steering. At which point you immediately pull over and figure out what it is.

Always easier to fix a problem immediately, than waiting until catastrophic failure. A blowout is the only failure you won't "see" coming, although they only normally happen with tires that should have been replaced long ago.

The valve stem holds the air in the tire. Inexpensive valve stem caps protect the (Shrader) valve from getting dirt in the valve.

The title says the cap is mission off the valve stem. Missing a cap is no repeat NO issue.

The tire without a valve stem is a TEMPORARY Spare tire that is only meant to get you off the freeway to a place where you can get your original tire repaired or replaced. If you drive with that temporary spare for too long then it WILL fail. GET YOUR ORIGINAL TIRE REPLACED.

no. it just keeps the dirt and mud out!!!!!

So I m an 18 year old female, and I work 5pm-6am, so around 7am I got stranded on 11 because my back tire went flat and I didn t know so it split. I finally was able to use a strangers phone because mine was dead. My boyfriends grandfather put another tire on it, this one does not have a valve stem. I m so paranoid that, that will happen again. I m pretty sure the other flat was caused because my rim was bent. but I just don t want to get stranded again, because I was terrified, aggravated, and tire from working a 13 hour shift.