My '05 tire pressure alarm went off just over a month after my purchase. It was after work on a day with a bad thunderstorm. Two minutes into my ride home, I heard the 10 second buzzer and then I noticed the tire pressure light. I live in an area where there is lots of construction going on, so I thought I must have had a nail. I pulled over and visually checked all four tires. I couldn't tell which one was causing the alarm to go off. I drove to the nearest gas station to put in some air. The gas station was a dive in a bad part of town, so when the pressure gauge on the air compressor read about 32 to 35 for every tire, I assumed the gauge was a piece of crap. My warning light was still on.

I decided to drive home and stop at another gas station to see if their gauge was any better. 15 minutes into the drive (sitting in traffic) the warning light goes out. I drove all the way home and used my digital gauge and all were at the proper level.

It hasn't happened again, but it sounds like others may have had the same problem.

My guess is that due to the thunderstorm, the atmospheric pressure must have dropped so low this it caused my tire pressure to drop below the warning level. Then as I moved away from the storm and my tires heated up the pressure rose back into the normal range.

(the above statement is total B.S.)