5mm 12 tooth gear mod to 4mm gear

Pressing the wheels out like that, instead of twisting probably doesn't remove too much of the inner plastic wheel, so, you could most likely get to remove the wheel 2 or 3 more times before the wheel becomes loose. If you mark the wheel on the inside to the axle you could press the wheel back on in a different spot every time you remove it so you can get "fresh" plastic bite.