Cork, Foam Rubber, styro-foam tires ?
Replace structural supports with bamboo ?
Set the wheels in the empty halves of a "belly" tank to slide along while on the ground and be left behind on takeoff.
Use pontoons, land on the water ?
Cover the field with 6 layers of 4 mill plastic, spray the whole thing with "oil", and come in wheels up ?

another hint ?

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"Danger Will Robinson!"