First set is width in MM. ~~285
Second is height in % of the width. ~~75
Third is rim. ~~16
So its 285mm wide, which is 11.2 inches.
Then you look at 75, which is the profile(sidewall from wheel to top of tire) and find out what 75% of 11.2" is. In this case, 8.4 inches.
Now double that and add it to your wheel size. 8.4 + 8.4 + 16 = 32.8" tall.
To answer your original question, now that we have the tire size, you will run higher RPM now. Should help fuel mileage around town and will feel a bit more perky from stops. If the speedo was geared for the 285s then it will now be a good deal off. It will show you are moving faster than you actually are.