225/75R16 is 2.44" shorter than 235/85R16, a −7.69% change in diameter. That is more than the 3% many tire shops use as a limit, so plan on recalibrating the speedometer and checking ABS and stability control.
Ground clearance changes by 1.22" (half the diameter change), and the tire needs 1.22" less room above it.
235/85R16 is 0.39" wider. On the same wheel offset about half of that, 0.20", moves toward the suspension and half toward the fender.
Both fit a 16" wheel; the sidewall is 1.22" shorter on 225/75R16.
Details: 235/85R16 in inches · 225/75R16 in inches · change sizes in the calculator