Ok,
this ALWAYS comes up...
so may aswell collect info from peoples experiences....
first of all.... tyre size calculator to make sure your speedo stays as acurate as possible...
http://www.miata.net/garage/tirecalc.html,
now in my experience...
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18" x 8.5" rim 35 offset, with a 225/40/18 tyre will fit on a lowered car with no problems.
if the camber fix/mod is done, the rear guards need to be rolled,
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17" x 7" rim 40 offset, with a 215/40/17 will fit with no issues at all.
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18" x 8" rim 38 offset, with a 225/40/18 tyre will fit on a lowered car with no problems.
if the camber fix/mod is done, the rear guards need to be rolled,
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please feel free to add what you know fits,