Is there really accuracy problem with speedometers if using P235/60R16 instead of P225/60R16 on 97 Olds Aurora

l think it might make the speedo more accurate.

yes there is it will throw out your drive train damage your transmission your speed odometer will be out

Yep. They have different overall diameters.

The P235/60R16 tire is 235 mm wide at its widest measured at the bulge in the sidewall. Its sidewall aspect ratio of 60 means that the sideqall height measurement from the rim to the tread is 60 percent of the 235mm tire width. Since the other tire is slightly narrower, its sidewall is slightly lower resulting in a smaller diameter tire. Smaller diameter means smaller circumference which means more revolutions to cover the same distance as the slightly larger tire. This equates to a difference in speedometer readings.

These readings have a percentile effect. meaning if u r ten percent off, u will only be one mile off at 10 mph, but u will be ten miles off at 100 mph.