Is there any advice on changing the wheel and tire size from 19 inch and 17 inch on my 2004 A8. And where can I find a similar 17 inch wheel. Will any reprogramming be required? Also the tire pressure sensor monitors inside the tire? Our special valve stems required?
Thank you for any help you can give me with this subject matter

 

Traditionally, folks tend to go UP two sizes, not down. But, since you asked, go HERE: http://www.miata.net/garage/tirecalc.htmland plug in the information from the sidewall of your current tire/wheel setup, in the left-hand set of drop-down menus. (It'll look something like 255/35-19, along with some other letters and maybe numbers that don't really matter, for THIS block of instruction.) BTW, the 255 is teh width of your tread, on your tire. The 35 is teh aspect ration, or teh percentage of tread width that is your sidewall height (in this case your s/w is 35% as tall as your tread is wide, or approx 89.25 cm). And teh 19 represents your wheel (NOT RIM, DAMNIT!!! NEVER RIM!!! If I EVER hear of you refering to your WHEEL as a RIM I will have aliens visit you in your sleep and probe you!!!) diameter.

THEN...

Fiddle around with the sizes in the right-hand side of drop-downs, starting with teh wheel (did YOU think RIM, just now?!?!?! STOPPIT!!!) size. What your goal is is to get the graphical representation of teh tire to fit within the outline of the graphical representation of your existing wheel/tire setup. I'd be willing to bet that, being an Audi and, given how lazy engineers are, you could VERY easily plug in the sizes for the 17" wheels from earlier A8's and it'd fit like a glove. Try 225/50-17. Stock 17" wheels for Audis are several hundred dimes/dozen, on eBay. The offset should even be mathematically correct, too.

As long as your rolling diameters match, from old to new, you will not have to reprogram your speedo. As far as teh TPS, I believe it's a device that's attached to the inside of your stock wheels, not the valve caps, that sends tire-pressure data to your dashboard. All teh valve caps do is hold teh air IN, not measure the pressure at which it's trying to escape. Absent the stock wheels, or a set of 17" wheels with TPS's already attached (good luck hunting for a set of those), I'm afraid you're gonna hafta monitor them the old-fashioned way... By getting OUT of teh car and looking AT the tire to see if you think it's low and, if so, breaking out the old manual tire-pressure-gauge to confirm what your soon-to-be calibrated eyes just told you.