where is your son riding it the most, and on what type of surface ?
eg sand, dirt, dirt/rock, race track etc?
and what is your budget?
are you looking for Steel or Alloy rims too?
what size axles does he run?
and what hub width?
obviously you can spend a lot of money on the front and rear wheels.
there are lots of options, Billet CNC machined hubs, Heavy Duty spokes, Different types of Alloy rims etc etc
They do fit yes. You need to modify some spacers. DHZ will send you some long ones that you can cut down. Its a very easy process.
Run the DHZ disc.
Get DHZ to send you the disc bolts to suit the DHZ disc.