http://cgi.ebay.com/ebaymotors/ACURA-AUDI-BMW-TIRE-WHEEL-PRESSURE-MONITORING-SYSTEM-NU_W0QQcmdZViewItemQQcategoryZ33746QQihZ013QQitemZ230071367056QQrdZ1QQsspagenameZWDVW

The other extreme is for racing applications or RV starting at $200+.

http://www.tirepressuremonitor.com/

Please advise a good system?  I am installing new 225x45x17" tires and would like to put a system on in the next month.  This is for a 97 328iC.  Regards, Tim.

Sorry, I'm still recovering from NYE party. What are you needing the temp/pres. system to monitor and for what reason? I'm sure there are a variety of options with a large spread of costs...

I have had several cars with factory tire pressure monitoring systems. Some were "neat" and had digital on-board, semi-accurate displays. Some, like recent BMWs, are dumb systems that use wheel speed sensors to find a tire that has lower pressure than another (inferring low pressure with a slower spinning tire, I believe). Even when racing a car having fancy direct pressure monitoring system, I still checked tires manually for autocross events.

When it came time to swap tires on the factory rims these pressure monitoring systems became a huge hassle. The wheel mounted tire pressure devices (pressure transducer + wireless transmitter) are large, cumbersome to work aorund, and expensive to replace. There are aftermarket options that mimmic the factory systems (thousand$). The tire shops have started charging extra to swap tires on wheels with pressure monitors (I found this out on our last RX8), and I suspect it is from replacing broken units. The wheel balance is also effected - the weight of the tire pres. unit must be offset with more wheel weights.

As for tire temperature monitoring - not sure what benefit this would give you, if wheel mounted wireless devices are currently offered. Would this measure inner wheel temperature? Tire air temp? Tire carcass temp? Surely not tire tread temps - at inner, outer, and middle of tread - like a real contact pyrometer would check. The air/carcass/wheel temps don't mean much, do they? Tread temperatures are what racers want to know.

A somewhat popular method for checking tire temps across the tread are arrays of IR sensors mounted in the wheel wells and tied into a data acquisition system. I have friends that have done this with the same DL-1 d.a. system we are using: real time tire temps at 3 places on each tire. Pretty useful data.

Again, what is the intended use for this data? Endurance racing, curious street driving, tire testing, solo racing, towing, RV enthusiast, or up-and-coming NASA scientist?

Terry Fair - www.vorshlag.com & www.ast-usa.com
"Alpha" E36-LS1 (XPrepared/G Class "No Class") '97 M3 (STU/F Class), '91 318is (STS/C Class)