I'd use what they tell you to use w/ their wheels!
I say this b/c if I remember right, they may need flat stepped w/ washer lugnuts and the centering step part needs to be the right length. If it's too long, it will bottom out and the wheel will still be mounted, but tight lugnut-wise, loose to the hub/axle flange!
I do know my Bullitts use stock Ford v-coned type lugnuts. Much different than my old Fenton slotted mags that use what I mentioned earlier. And make sure the washers don't break!