Glue the track links on. Twenty single track links will be sufficient but will leave a 2mm gap. Spread the links out (don't butt them up against each other so tightly) to eliminate the gap. You can use a single double track link to show where the Wheel contacts the ground if you want the illusion of more weight. Just file one section of the base edges a little flatter and be careful to space all the track links out to fill the gaps.