Look at a 1990 Miata fitment, you'll see all of the 15" sizes listed. The 15x7.5 only comes in grey, there may be a drop-down.
All of the 7-8" ones are the C1, and the 9" model is the C3M. There is a +30mm 15x7 called the C1M as well. Keep in mind that the M-suffix versions have Miata-specific hub bores, which will be a problem for your Honda.

