Speedometer read-out

[gigdy]

from what ive learned when you go up an inch in wheel size your tire size should change like this.

205/55/15
215/45/16

i changed the tires on my car for 55 to 50 series it made my odometer be about 4-5mph slower

[SamuraiGti]

I changed from 185/60(or 65 don't remember)/14 to 195/50/15 and I didn't notice any changes on the speedometer, maybe a little slower but nothing special.

[crazyxzer0]

If the incorrect size tire is on the car, does it affect anything else besides the speedometer?

I recently got some rims and the radius of the 15inch rims dont match my old 14inch rims. Its an inch off. Are there any negatives besides the speedometer being off ? (tires are really new and don't want to waste them)