Greetings - I have a Rans Vivo with 406 (20 inch) rims and I run a Big Apple 20x2.0 in the front and a Marathon 20x1.5 in the back - I found that the soft sidewalls on a Big Apple make it an inefficient rear tire - the flexy sidewalls suck a ton of pedal energy from forward motion, and they're simply not fast back there. However they are magic for rolling resistance and ride, and quite exceptional in front. The Marathon has a stiff, bullet proof sidewall, which is quite efficient in translating pedal forces to the wheel, and they are resistant to anything this side of Kryptonite. Plus they have exceedingly low rolling resistance. The Marathon can be a bit harsh at high PSI (I run mine around 95 PSI on tarmac), but the Vivo is fully suspended, so I barely notice.