The white stock wheels on the flowboards are horrible, first thing to do is getting the upgrade wheels.
For more speed, deffinately look out for 72 mm wheels, I wouldn't pick the 59 mm ones that are currently on there homepage - although the urethane probably is better than the stock wheels.
If you live in Europe: sickboards still sells the former yellow "high premium" upgrades (72 mm, 80a). check them out here:
Flowboards High Premium Wielen | Sickboards Longboardwinkel
The counterpart on the 72mm wheels is that they result in a wider gap between the wheels, making the transition a bit less smooth. That doesn't weigh up to the fact that they make the board ridable, instead of being forced to constant pushing...
Oh, I wouldn't advice anyone to actually buy a flowboard, but if you got one you might as well make it ridable.
(The best way still is to put some conventional trucks under it and take it to the local bowl to have some rippin fun)