Brian, I posted this over on the forum, but wanted your input as well.
I have a pristine set of [black] Volk RE30's taken off my S2000 before I sold it last year. The only compelling reason for mounting these on my MX-5 is that they are lightweight, good-looking, and FREE . I do know all about the problems (and compromised handling) with mounting a staggered set of tires on a Miata. However, I also have access to a set of four (4) nearly new 235/40/17 summer tires that I am thinking about mounting. I know the front wheels are slightly narrow for a 235 (17x7.5 +50) but others have mounted similar tires on 7.5 rims with no fuss. The rears are 17x9 +63 and will [definitely] require a 5mm spacer (to +58) to get them to fit with no inside (or fender) rubbing with the same 235/40/17 tires. I am currently lowered to 13.5" f/r with -2.0 camber all around.
Again, my only expense will be the $60 for mounting and balancing, probably more than offset by a sale of the NT01's [to the S2000 track folks] currently on these wheels. Again, this is only an experiment, as I am quite happy with my Enkei's and Michelin Super Sports. And I'm tired of sitting on these beautiful Volk wheels that no one seems to want. Thoughts?