Door opening and closing control information transmitted from a portable transmitter 3 is received at a receiving apparatus 20 to drive a door locking mechanism 4. A tire sensor unit 10 mounted on each tire 2 detects tire pressure and tire internal temperature and radio-transmits those data and identification...http://www.google.de/patents/US7019628?utm_source=gb-gplus-sharePatent US7019628 - Tire monitoring and keyless entry system
