3. Buy HD wheels$44.00, sleeves, washers, bushings$22.00 and pins and hope it works at approx. $80.00
It will work. My Trax1 cart with the HD wheels has done over 1200kms on 3 sets of wheels (original Hobie HD upgrade, locally sourced pneumatic and now Wheeleez HD) The HD foam wheels are my favourite. It's great not to worry about punctures.
I like the solid wider axle on the Trax. Remember the HD wheels will fit the Trax cart but you can't add the balloon wheels to the HD cart easily (unless the HD axle specs have changed?).
I mostly use the HD wheels on hardpack but it's handy to be able to swap back to the balloon wheels when travelling over sand.