I know quite a bit about cars and how to work on them but the one thing I have no clue about is tires. I need to get knew ones and started wondering what made for a good ride or quite ride. I have 20" rims and right now my current tires are 255 50r20. I know I have to get a tire for the 20 but what difference does the 255 and 50 make and does it have anything to do with how smooth and quite the ride is?