Just some ideas.
"Belt drive robot" - "direct driven center wheel"
Unless andymark has aquired new belts, there are currently only two sizes. The 20.47in belts are not large enough to accommodate 6in wheels or larger(and I imagine they might be using their new
6in HiGrip anyway). Because it is a direct driven center wheel, the outside wheels are the pulley center distance away from the middle wheel(minus the 1/8in center drop). Inferring we are using the current pulleys and the 31.5in belts, the center distance is about 11.5in.
Soooooooooooooo
(11.5in * 2) + (3in(HiGrip radius) * 2)
= 29in
Possibility the new drive train is at least 29 inches in length.