I am in the dog-house. My wife bought some valve caps that have indicators warning of pressures. I installed them yesterday and just to make sure they could not be easily removed/stolen I cranked them down with a wrench. Today we had to make an emergency stop as her tire pressure warning light (which neither of us realised her car had) came on. On investigation I found all 4 tires were almost flat. We limped to a fire-house and were lucky to get some assistance. Now I have been quoted $420 for new valves plus fitting and alignment. Her RX 330 is a 2006 model, can we install regular valve stems and what effect would this have on her onboard computer? Is it legal to remove the TPM system? Is this a fair price or can they be bought somewhere other than Lexus. Need some help here, our doghouse ain't that big. Thanx