67" is great for those learning to skid. but too low to be practical imo.

interestingly upon looking at this chart:


i realized it is wrong, w/ gross errors in calculation.

i'm currently at 53x18 which is a tad bigger than 44x15 (previous ratio). you'll see that's not reflected in the chart. hopefully no one uses this one.

this is the better one: http://rideyourbike.com/images/skidspots.jpg
uses the default 27" as the wheel diameter constant as well