FALSE. Road grip is determined by the amount of rubber that comes into contact with the road surface and the stickiness (hardness or softness) of the rubber compound.
FALSE. Tubed or tubeless is determined firstly by the construction of the wheel rim and secondly by the type of riding you do e.g. sportbikes used tubeless radial tyres as they are safer at high speeds. Off road bikes with their spoked wheel rims generally use cross ply (bias ply) tyres with tubes
FALSE. Under-inflated tyres grip the road better but there is a price i.e. excessive heat generation at speed. An under inflated tyre can overheat with a possible blow-out being the result. Conversely, over-inflated tyres run cooler but do not grip as well.