yes it supports it as any other joystick and better now that some updates ago the analog vehicle movement was improved.
Anyways its not really that usefull unless you are going to be all the mission as driver since when you jump out the vehicle or in you may need to take the wheel and drop the mouse and its a bit troublesome, specially if you are under fire, i can assure you it can get really messy :P.
The real advantage on having a steering wheel its more on the pedals, since the analog steering with the mouse its already good if you want that kind of control. The pedals give you better control over you velocity and allow you to keep slow speeds easilly. You can also use the pedals for flying, so thats another use.
So if you already have a steering wheel and you want to test it with arma, do it. But i wont recomend you to buy it just for arma since keyboard or even mouse control(personally dont like it) its more than enough for ground vehicles.