Quote Originally Posted by REPPHD View Post
225 50 R15 would be 23.7 OD sames width.
225 45 R15 hoosier is 22.9" diam.

At RA I run the 4.73 gears. Now I know I could go back to 4.11 which would change the rev pattern and that is an option for next year.
taller tire is like going to a smaller gear. doing both would be murder unless you stepped down the gearbox and even then it rarely works out well as the spacing tends to increase in the bottom of the box. what you are talking about is a ~10-15mph change in 4th gear speeds at 7k RPM, and less acceleration on the way there.

So I think what you are telling me is it possible; we fixed the rub on the Kumho 14's early on; The 15 inch wheels I think are good at about 11 lbs are 35mm offset (miata). Bigger tires weigh more, but wheels keep total unspring weight gain to a minimum.
just be careful, Miata wheels are 54mm center bore, honda is 56. also, most of the Miata wheels I've seen are +45mm offset. spacers can take care of both problems though.