[Txturbo]

All depends on what you use the car for. If you want better handling and feel for the road, a shorter sidewall is better but you may not get as much traction for drag racing. If you want taller sidewalls to soften up the ride and allow you to lower the pressure for better off the line traction you will lose some feel for the road and its gets mushier in the turns. But also, there is no rule that says you have to have short sidewalls with a 20" tire. They come in 50 series also. You just have to recalibrate the speedo to maintain the accuracy if you want both because you will increase the height of the combo. Which isn't always a bad thing, if you want to change the rear end ratio without changing the ring and pinion gears.