2005 Aftermarket Wheels, Tire Pressure Monitor, and ABS Question

[soldierguy]

Is the Tire Pressure Monitoring System something in the wheel that monitors the actual tire pressure? Or is it the ABS monitoring wheel speed and alerting the driver when one wheel is spinning consistently at a slightly different speed than the rest? Also, if the TPS thinks there's a tire with low pressure, does it just turn on a warning light?When I ordered my 05 GT, I noticed that the ABS was standard, along with a tire pressure monitoring system. Thinking that the TPS was a thing in the wheel that actually monitored pressure, I also ordered the 17 inch wheels even though I'm not too fond of the look of them. I prefer the look of the 16's, but know that I want 17 inch wheels. My original plan was to order the car with the stock 16's and then install some lightweight aftermarket 17's, but I kinda like the idea of the TPS and don't want to screw it up somehow or have a constant warning light on the dash if I install aftermarket wheels & tires. I know the TPS is linked to the ABS option...you can't get one without the other on the 05's, and the thought that it might just be the ABS monitoring wheel speed just hit me.If the TPS is just the ABS monitoring wheel speed, I'll probably switch back to the 16 inch wheels on my order, and put the $400 towards aftermarket wheels & tires.Thanks in advance!

[futseal04]

TPS uses the ABS system to monitor tire pressure. It does this by:On each wheel is a wheel speed sensor. Different brands have different types, but they all work the same. Basically, as the tire rotates, the sensor parts create either a sine or step DC wave. The frequency is directly proportional to wheel speed (i.e. higher freq, faster speed.) When applying the brakes, if the freq. goes to 0, then the wheel has stopped, and the ABS computer regulates a soleniod valve to allow the tire to rotate again. (That is the pulsing you feel in the pedal).Since we have this indication of how fast a tire is spinning, we can use that to deduce tire pressure. A tire with less pressure will have a reduced diameter and therefore, rotate faster than the others. I haven't seen the Vibe's setup, but on my Grand Ams, there was a procedure in the Owner's manual that allowed you to recalibrate the TPS. I am sure the Vibe's will be the same though.......

[soldierguy]

I figured that's the system the Vibe had because the wheel choices are the same for the 03 through 05, but the TPS just came about for 05 and it's available only with the ABS. Just wanted to verify.If it looks only at differences in wheel speed then the system shouldn't flip out and start throwing warning lights if I were to swap wheels & tires. At least that's what I'm hoping because I'd really like to get some decent aftermarket wheels that look better than the stock 16's or 17's and weigh less.

[MadBill]

The majority of GM TPSs use the ABS sensors. Corvette with run-flat tires and maybe some others use transmitters mounted in the wheels and you get a corner-by-corner read out of actual pressure. (BTW, the ABS-based systems are no help at all if all four tires are soft, say due to a 50 degree temperature drop in about 3 days... )

[GMJAP]

Quote, originally posted by soldierguy »If it looks only at differences in wheel speed then the system shouldn't flip out and start throwing warning lights if I were to swap wheels & tires. At least that's what I'm hoping because I'd really like to get some decent aftermarket wheels that look better than the stock 16's or 17's and weigh less.There is a button on the '05 to "calibrate" the TPS system after installing new tires or toppping off the pressure or fixing a flat, etc.So you can use this to reset the system to your new wheels without any problems.EDIT You can read about the TPS system in the 2005 Owner's Manual, posted at the bottom of this thread:http://forums.genvibe.com/zerothread?id=1010

[GMJAP]

Quote, originally posted by MadBill » (BTW, the ABS-based systems are no help at all if all four tires are soft, say due to a 50 degree temperature drop in about 3 days... ) In fact, there no good if 2 tires on the same side are soft, since it can only compare same-side front to back (side-to-side speed changes when turning).Still, better than nothing and on an inexpensive vehicle like the Vibe, you usually get nothing.