Low profile tires suck! Unless your mario andretti
First lets look at tires size and what that means 215/45/R17. The first number 215 is a metric number or 215 millimeters and measures the from sidewall to sidewall on the tire.
The second number is a percentage. In this case 45%. For example, in a size P215/45 R15 tire, the 45 means that the height is equal to 45% of the tire's width. The bigger the aspect ratio, the bigger the tire's sidewall will be. 45% of the 215 millimeters = 96.75 milimeter.
Switching to a to a P215/50 R15 will increase your sidewall 215 x 50% = 107.5 mm. So you would go from a sidewall height of 96.75 mm to 107.5 mm. A increase of 10.75 mm. To convert to inches here is the formula. 10.75 mm x 0.03937007874 = .42 inches which is almost 1/2 inch.
Not sure less than 1/2 inch of sidewall is going to result in a much smoother ride but it will help.
THE LOW PROFILE TIRES ARE MADE FOR GRIP NOT RIDE. BUT THEY LOOK COOL BECAUSE YOU CAN USE A LARGER RIM. UNLESS YOUR GOING TO THE TRACK NEVER BUY A CAR WITH LOW PROFILE TIRES. I was given a loaner car from a dealer with these low profile tires while mine was in the shop. I drove about a half mile turned around and told the dealer that I cannot drive 200 miles with a car that rides like a lumber wagon, the idiot from the dealership argued with me and so I made him go for a ride in that car and then in another with regular tires and he couldnt believe the difference. And he sales cars?
ALSO BEWARE THAT THE PRICE OF THESE TIRES THAT ARE LOW PROFILE AND FIT A LARGER RIM ARE VERY EXPENSIVE. TO REPLACE A LOW PROFILE TIRE ON A CORVETTE IS GOING TO COST YOU UPWARDS OF $400 PER TIRE.