difference between 215/55/17 and 225/55/17? will i notice anything different?

 

215 and 225 are the widths in mm.

55 is the aspect ratio, which is the % of the width of tire
118.25mm sidewall thickness (215)
123.75mm sidewall thickness (225)

that's only 5mm difference...you probably won't notice much other than
a more comfy ride on the 225/55's.

 

10 mm width

and with a 55 aspect, you will be adding about 5 mm to your sidewall.

A better tire would be 235/50/17, which will add 20 mm to the width and hardly anything to the rolling circumference of the tire.