I've got 40 x 16 and I find it's too light for this flatlander. Maybe 42 x 16 (which really wouldn't be much of a change). I ride 46 x 18 on my singlespeed which I think is perfect.

I used to use only one brake, but as I like to ride on the hoods, I hooked up the rear brake for symetry. Now I find that I like to slow down with the rear brake and stop with the front.