I've got Falken Azenis 195/60-14's on my '74 & '87 Spider's, and I think they're about the best tire I've ever had on a Spider. I just bought the set on the '87, and paid $270 with mounting, balancing, and tax, so they're a great buy, too. They are however 1/2" smaller in radius than a 185/70-14, but that hasn't been any trouble, even on my lowered '74 Spider. I've only driven them once in heavy rain, just out of curiosity, and they're usable, if one is aware if their characteristics and avoids standing water. Can't comment on wear, as I only drive each Spider a few thousand miles per year. Here's a handy tire size calculator, if anyone's interested:
http://www.miata.net/garage/tirecalc.html
Regards,
Dean
Lutz, FL
'74 & '87 Spider Veloce's