once your levelers hit the ground, they are already 'supporting' your RV, so whether the wheel is 'still touching the ground' or 'completely in the air' makes no difference.
some will argue that it's not 'comfortable' to them, and therefore they want to try to put something 'under' the wheel, like a piece of wood, or concrete block, but the fact is that it makes no difference whether you do, or don't. The laws of physics don't change simple because we think something 'looks' better, or safer, to us.
some will also argue that front wheels off the ground is o.k., but a 'no no' for the rear wheels... I suppose due to the thought or belief that the rear wheels are really what 'anchors' the coach, or provides the 'braking' in the event the coach were to go 'rolling'...but the front wheels also have brakes, so therefore there is really no difference.
also, as a note: when the coach is LEVEL, it has no reason to 'go anywhere', no matter how it looks or whether a wheel, or wheels, are 'off' the ground. Anything that is level has no reason to move, even if you are moving around inside of it - you don't have enough weight to throw around to make much difference, even though you might feel some slight movement of the coach inside.
When your coach is level, your brakes don't need to do anything.
On the other hand, if your coach is not, and it is not leveled, then your brakes will have to do ALL the work to keep it from moving.
'14 Palazzo 33.3 bunkhouse 34' diesel
KingTailgater2 Dish HD, 100w/5a SOLAR, BlueOx
100,000+mi since '14 - US, Alaska, Canada - Hiawassee, GA! (also, '14 Gulfstream Amerilite and '07 ForestRiver Rockwood) : )