I just tested the pressure sensor issue first hand. I lowered the pressure on one tire and watched what happened. First, you can hardly notice visually that it has no air. While driving up to 50 MPH it is real noisy. Over 50 you do not hear it any longer as wind/motor noise becomes dominant. Handling is amazingly good.
BUT, you cannot go into Performance Driving mode any more! Which is ok if you have a real flat. Not having any pressure sensors at all will do the same thing I expect – no performance mode.
So yes, I suggest getting sensors for your aftermarket tires/wheel combination.
See also posts here
http://cadillacforums.com/forums/showthread.php?t=18925
