Hi Hopster & All, in my 3120 manual, it gives me 8 different tyre positions ( if u have "Dished" wheels) in my manual its under Service Miscellaneous. when my tractor arrived, i too felt the unit was too unstable, dealer turned wheels around (ie dish outward) then changed the rim attachment to the inside - now my tyres run partly outside the mudguard line, but is much more stable - check what width u can achieve b4 buying spacers - might save u a good few $.
cheers Oz GH