This weekend (after driving ~200 km), I noticed the lip of this wheel disc looked like it was curling a bit, presumably because of the sidewall bulge at the contact patch. (The disc diameter is wider than the rim diameter.)
Thought process:
"But why is it just the one disc? Mysterious."
"Better check the air pressure..."
"Rats! My pressure gauge is broken! The slider bit with the numbers on it won't pop out."
Checks another tire...
"Oops!"
Looks like I'd been driving around on a
completely flat tire for who knows how long. (Admits the guy who poo-poos the necessity, cost & complexity of TPMS.)
CRAP! I will see myself out and turn in my membership at the door.
(In my defense: the car still seemed to roll OK. Also, the tire didn't look obviously flat. Maybe these tires have stiffer than usual sidewalls.)