text: All 4 Tires are Losing Air !?! | Second Generation Nissan Xterra Forums
  All 4 Tires are Losing Air !?!
  This is the 2nd time in the past 3 weeks that the TPMS light came on. Both times I checked tire pressure to find that I was 10-15 PSI low. The first time I pumped them back up thinking it was the cold weather. This time I drove to work (8 miles) to see if warming the tire up would turn off the sensor but it didn't so I pumped them back up.
  I was thinking it would be a leak, but that seems unlikely since its all 4 tires. Any ideas? TIA
  Are they new tires? Have you had any maintenance done recently?
  The tires are a year old, I rotated them 2k miles ago, nothing much else.
  Valve stems not reinstalled tight enough?? Pretty strange losing 10-15 psi
  I'm wondering if your valve cores have worked themselves loose... 10-15 PSI is a lot, even for weather changes.
  Are you checking them when the rig is completely cold each time? Your tire pressure can come up a fair amount while driving and doesn't go down for a while, so make sure you're doing an apples-to-apples comparison.
  Also, what kind of tires do you have, and at what pressure do you normally run them? Has the spare also lost air?
  Check the inside of the valve cap, someone may have screwed with you and put small pebbles in the inside just enough to let the air seep out slowly. Just a thought as I would do it to my buddies when we were younger on there bicycles.
  Piss a neighbor off recently
  hahaha... reminds me of some buffoonery from when I was younger.
  Are you 100% sure nobody is messing with you? This is exactly the sort of thing I would do to punk a buddy if I knew it would drive him nuts and could watch (and laugh about it over a beer later- I'm not malicious toward my friends.)
  TPMS sensors? they tend to leak after a few years im on my last 2 wheels that I haven't changed over to rubber stems yet (its frowned upon and most shops won't do it though)
  When the temperature outside drops, the air pressure in your tires drops also. I see you are in California....Have you had a cold front roll through?
  2 or 3 pounds perhaps...NOT 10-15 (unless he hasn't checked them in a few months)
  Correct, 1 psi for a 10* Fahrenheit drop, according to Tire Rack tech article.
  ^^I always have to add a little air at the onset of "winter".
  I had a brad nail in 3 of the tires causing a very slow leak, must have picked them up all at once on the road. The 4th tire was probably just low.
  Pulled them out and plugged the holes, everything seems ok now.
  I was going to ask if you had driven by any construction sites or roofing jobs lately. Glad you found the problem and it was an easy fix.
  Glad you found your issue. An external tire plug is typically viewed as a temporary fix. A more permanent fix would be to do an internal tire patch (removing the tire, and applying a patch from the inside).