Just had my tires rotated and after some highway miles, the tire pressure warning light came on. On the rotation, I had them include the spare. I've checked and added air so they are all the same and reset the sensor, but it's come on again. Is the reason I'm having problems that the spare has more tread depth? I'm thinking that it is rotating fewer times than the tire on the other side with less tread. I read somewhere that our tire monitor system on the '04s just measures tire rotation, not pressure. If the tires aren't rotating the same, then the system assumes one of them has less/more pressure than the other. Anyone else have this problem? Should I just forget rotating the spare to keep the tires the same on both sides of the axle?