Here is some more information.
On your 1991-93 OEM NSX wheels, they wheel sizes are 15x6.5 front and 16x8 rear, with 205/50-15 and 225/50-16 tires.
With the OEM tires, starting with the front, the 205/50-15 tire size will fit on a wheel width range of 15x5.5 to 15x7.5, though the optimal wheel width is 15x6.5, which is what the OEM front wheel is. Now, on a 15x6.5 OEM wheel, you COULD put a 225/50-15 tire on, and it would fit, since for this tire size, the wheel width range is 15x6.0 to 15x8.0 (pretty wide range), but the OPTIMAL wheel width for a 225/50-15 tire is 15x7.0. So, in this case, it would fit, it would work, but it is not optimal. The other thing to consider is that if you switch from a 205/50-15 to a 225/50-15, you will be increasing the rolling diameter by 3.4%, or 0.8", and your sidewall will be 0.4" taller. This will affect handling over the OEM size. Yet another issue is that the OEM tires are corner specific and have an internal bias built it in improve handling and steering response. When you move to a non-OEM spec tire, you automatically lose a bit of handling and response, ceteris paribus. On top of that, continuing this thought, increasing the tire size alone will further take away from handling and response/performance.
You can do the same calculations for the rear wheel/tire if you want. These are just my opinions, most of which are based on experience and common sense.
Cheers.
[This message has been edited by weiku (edited 06 December 2000).]