I just picked up a new A4 sedan and underdstand that it has TPMS unlike my 07' Avant s-line. Since the snow will be falling soon I'd like to switch out to my winter tires (mounted Dunlop D 3's. Does anyone know what would happen if I did not have the TPMS sensors installed into my snow tires or will I need to spend the $400 to retrofit my snow tires with only 3k on them. Thanks in advance for your input.

 

I currently have a 2007 S-Line with TPMS and winter tires without it. It is a pain in the *** because you have to keep going into the menu and tell it you have "changed the tire" every 10 minutes or the yellow TPMS symbol stays on the screen. You can disable it if you have access to a VAG or get your Audi dealer to do it each winter - but they charge each time - which in my opinion is BS as it takes about 45 seconds - especially after I retrieved the code for them!!

 

I've never had TPMS but I asked the dealer what they though of running without TPMS on the winters. They just said to swap the sensors, because they run over 200 for a spare set and if you don't use em, you have to deal with the annoying sensor messages you've described.

 

As I understand it, the 09 A4 doesn't use pressure sensors, but instead relies on the ABS/electronic stability sensors to let you know when a wheel isn't spinning the same as the others, that being the symptom of different tire radius caused by low pressure. When you change tires or tire pressures, you use the MMI to enter the new constants.

 

though coming soon. Can anyone who has taken delivery confirm? Also, changing out sensors would be expensive too since a shop would charge for that service (2x a year would add up). It may be easier to buy new sensors.

 

The 2009 B8 A4 uses the valve type pressure sensors and it would be a pain to remove them and then to reinstall.

I do not have them on my 2006 A4 that has TPMS. I agree it is a pain to see the yellow warning light all winter long. I may invest in a VAG. It would be much cheaper than buying sensors for both my 06 and 09 A4 winter tires.

 

Audi has forged a partnership with a company that uses advanced algorithms that will preclude the need for physical sensors but not yet deployed in current models. Audi told me they don't know when and which models will use the new system.
For now, we are stuck with mechanical senors.

 

I quote from the UK A4 owner's manual (perhaps this system didn't make it across the Atlantic):

The tyre pressure monitoring system makes use of the ABS sensors to compare the rolling circumference and the vibration of the wheels. The display in the instrument cluster alerts the driver if changes are detected on one or more wheels. If only one tyre is affected, the display will indicate its position -fig.27.

Each time you change a tyre or the tyre pressures on your vehicle, you must store the new tyre pressures via the sound system or MMI* - page41.

The rolling circumference and vibration can change if:
* The tyre pressure is too low
* The tyre has suffered structural damage
* The air pressure in one or more tyres was changed and the new tyre pressures were not stored - page41, "Storing the tyre pressures"
* The wheels were changed and the new tyre pressures were not stored ?page41, "Storing the tyre pressures"
* There is a greater load on the wheels of one axle (e.g. if you are carrying more passengers or luggage)
* The road surface under the left wheels is different to the road
surface under the right wheels for a long period
* It is the driver's responsibility to ensure that the tyre pressures are correct. For this reason you must check the tyre pressures regularly.
* Under certain conditions (e.g. driving at high speeds, on ice and snow or on poor road surfaces) the tyre pressure warning lamp may not light up immediately or not at all.

 

thus, our cars are currently using the active TPMS that sends current tire pressure info to the computer, just like snagitseven has said and other members.

It would be nice if our cars had the passive TPMS system that relies on calculated circumference for each tire.