We have bigger brakes on the 06+, so we have to run 16" or 17" wheels to clear them. The car is styled for 17" wheels, so it is proportional. Your wheels are not so much of an appearance issue (other than in comparison to other NA miatas), but many people will comment on them because they are HEAVY, and that generation Miata is very sensitive to unsprung weight. It will handle and ride much better with a proper size wheel.
Put those on Crailgslist and you'll sell them to some Honda ricer kid in no time, for more than enough $$ to buy a decent set of oem Miata wheels/tires. Someone already offered a great rim deal, and I think POS has some like-new tires for sale.