A 195/40 16 side wall will be too small and it will change your gearing too much. If you do get a 195 width tire, which I don't recommend because a 205 is better and wider, you should get a 195/50 for best fitment to stock. You should get a 205/45 16, because this size is very close to stock and its a 205 width instead of a 195. The overall goal of tire sizing for the street is to get tires that give you the same overall tire diameter as stock so you don't change your final drive ratio. I use this tire size calculator, with 195/55 15 being the baseline-
http://www.miata.net/garage/tirecalc.html
I've used toyo t1 r's before and the side wall isn't very reinforced (1 polyester ply vs. other tires with 2) so they had mushy response, but they were alright for grip. I would choose the Goodyear eagle f1 gs-d3 in 205/45 if you like the toyo t1-r, the eagle f1 is a much better tire. If you want something a little stickier than the goodyear you could try the kuhmo MX (220 wear rating). If you want
some rainworthyness along with a maximum amount of grip try the hankook ventus RS-2 (200 wear rating) If you want maximum grip from a street tire you could try the Falken azenis rt-615 but they aren't good for standing water (also 200 wear rating) Wear ratings are a loose number giving you a good idea how long a tire will last, the lower the # the softer the tire. You're going to want less than 300 for a tire with good grip.