Ill take pics later, easy but blooming anoying, here is how to do it
Parts, 4x small round magnets
2x 3mm boltsx15-20mm have to mesure them and nuts
Tools, hammer small punch rod, twesers and small fine flat screwdriver and philips screw driver, hack saw, SHARP knife
Ok unscrew the jd to get the back axle out, pop of the wheel covers , put wheel on edge of bench, gently punch the axle rod down to remove the plastic C clip type thing, turn over do the same for the other side, cut around 2mm away from the circlip grove, just enough so there is still taper on the end of the axle, do it to both sides, ( they have a poxy new axle, pointed both ends and has a stupid plastic circlip thing) put inside wheels on axle, place cir clip in with tweasers and push with flat head screw drive till locked in ( if you bugger the clip you have to glue the wheel to the axle nut on the inside)
Cut the tube bit of the inside of the wheel cover, fluch with the disc, place on magnet in the well then replace wheel cover, repeat
Now take the Plastic tube bit from the cover and fit to the Hex side of the Dual wheel, cut flush with the orignal height of the hex surround, do the same for both, place the bolt thru the axle hole and tighten upm making sure the nut is on the iside of the weel cover, file the head of the bolt flat, atach second magnet to this, ( one magnet will hold for moving but wont if you pick it up) replace the outer wheel cover, and you have magnetic removable duals
Then replace axle and rescrew tractor, Then you have a 7*30 with magnetic remoavble duals
ill take some pics of it later to show if any one is stuck just ask me