I have the 20x1.35 = 37-406 Primo Comet Kevlar tires on my WizWheelz 3.6 Tour model and the 20x1.50 = 42-406 Primo Comet Kevlar tires on my wifes WizWheelz Cruiser model Trike, so far so good on both trikes.
9-30-06
I made a tire change & changed the rear tire to a 20x1.50 = 42-406 Comet tire and left the 20x1.35 = 37-406 Comet tires on the front, I like this combo better, pic on the right side shows this change.
Thanks in advance and take care,
Bill G.