I will concur that the Pirelli Pzero Nero summer performance tires are simply amazing - if you and your suspension are up to it, these tires will let you do it....

I have run them for years on a Jaguar I just got rid of (so I could get my Audis :-)) plus a friend out in Etiwanda (sp?) CA has a set of them on his Ferrari, and when we swap stories about those tires, there's nothing but amazing accolades for this tire.

My preference is to run them on very light weight, high strength 18" wheels - this combo limits your road hazard bendage/breakage and still performs extemely well. Anybody running them on 19s? How much rubber do you have between the wheel and the road (i.e. what size tires ya' running?)

Since I've got 100 miles on the clock on my new A4 with Pirelli 235/40 R18 P6 95H M+S OEMs, I'll be getting a set of 5 Pzero Neros and another 5 rims for my summer rubber when ever MNDOT decides that they're done salting the p*ss out of the roads. Next fall, these M+Ss go back on, and the cycle continues....

 

The Avons start great but wear really really fast.
Mine lasted 25k miles before I had to replace them (noisy, not much tread left).
I'm on Michelin pilot exaltos now, they are better in the snow and the ride quality is also better. We'll see how long they last.

 

The 16's have a diameter of 24.9", the 17's have a diameter of 25.3".
http://www.miata.net/garage/tirecalc.html


I ran them all last winter, all summer (in 115ยบ+ weather), and for all winter up until now. They ran GREAT in the snow when new, I had to try pretty hard to get them to slide at all. They have really soft sidewalls and don't grip as well as they could in the summer, but they're winter tires, how much could I expect? For the last ~3,000 miles I've driven on them with serious toe in (bad alignment) and they're basically bald, but can still hold their own in the snow, haha.

I'd highly recommend them.

edit-
And they're pretty good in the mud, see sig.