[Jim Sims]

Does the TPS on the vehicle directly measure tire pressure? The systems I know about actually measure wheel rolling radius using the wheel speed/revolutions output from the anti-locking brake system. If one of the wheels departs too much from the average, the system assumes tire pressure is low somewhere and triggers the warning light. When my daughter ruined a rear tire on her car and when we replaced it with a new tire (same exact tire) the difference in rolling radius between the new tire and the others with 10,000 miles on them would eventually trigger the low air pressure warning. There was never a tire pressure problem so after checking tire pressure she would just reset the system.

I would go by the OEM specifications (using an accurate gage); these were set to optimize ride, handling and fuel economy.