I believe my 53 Skoda Superb is related to that age of Audi A6 and also has 205/55 R16 91W tyres. I do a higish mileage and have tried many different makes of tyres over the years - including Bridgestone(originals), Goodyears, Michelins + some poor cheapies. The cheap tyres were awful, the Bridgestones were OK but only lasted 18k.The Goodyears seemed better but even when I had a lot of tread left I was given an MOT advisory as at towards edges of the tread pattern there was a step up in the tyre base which effectively gave you much less tread for part of the tyre within the legal 2/3 band even though almost all of the tyre was over 5.5mm!!- i.e. they only lasted 16k!! I wont buy those again.

The Best by far have been Michelin Primacy HPs which on the front last 33k (to 3mm) and the rears much more, these seem to handle well and are great in snow and ice (I have a lousy commute!). I now won't buy anything else.

I have an 1998 Audi A6 quattro avant which has now done 142,000 miles and is the best car I have ever had (and I've been driving since 1947)

Dont let the VaG bashers hear you say all of this John !!

(I drive my second A4 Avant)

Can't recommend the Michelins enough. That's all I use now - and they last for ages. I have around 20k to do each year, so I get through the tread well before they are too old.

My local tyre place, which I trust having tried a few, supplies them but I have heard them dissuading an elderly gentleman from buying them on the grounds that 5k a year might mean that the tyres would be passed their best before the tread wore out. Worth bearing in mind if your mileage isn't too high.

I've been really impressed with the mileage though - it's not psychological because they are nearly the most expensive non-winter tyres - they really do last longer and I think the performance is great.