Conveniently, one of my coworkers had a set of wheels/tires sitting around that he took off his Miata before selling it. He let me have them for $100. Score! As you can see below, they are a little more sporty than my old tires.
Here's where things get complicated. The wheels he had are kind of heavy, so I've continued to look for lighter wheels, of which I found and bought two. Here's the various wheels I was working with.
|Clockwise from top: 15x8 6UL 195/50 R15 (29.8 lbs w/tire, 12 lbs without), Stock Miata "Daisy" 185/60 R14 (26.6 lbs w/tire), 15x6.5 Generic Wheel (32 lbs w/tire, 16 lbs without)|