Wheel base was too large

RTA only allows the wheelbase to be about 20mm or so larger than standard. anything greater is defective

 

you meant the "track"? (ie. the horizontal distance between the centre lines of the wheels across the width of the vehicle)...

wheelbase is the distance between front and rear wheels (centre of the wheels).

what's the offset of the 20" and what was the difference between the factory & that 20" setup?