I've had my chocolate sponge cake & custard, Im all better now
(sorry about that, it was a long day at work and yes I do need to get laid thanks, anyone got a spare 16-25 y/o daughter I can borrow?).
When using larger diameter tires, especially heavy ones (relatively speaking), gearing down cures most ills; 40-45mph is a nice zone to be in for any given combo/setup, controllable speed and lots of power still given a decent electrical setup (good lipos and torquey motor). Anything faster than that and gping lightweight is important to reduce the load on the esc and batts, since tall gearing will pull alot of current, so the less strain the better.