There are two distinct families of Tundra tire "Rig's". Those made by Rolligon, and those made by Nodwell/Foremost. The Rolligon's call their tires an "Air-Bag", they run up to 80" wide and are driven by a roller that presses against the top. The roller is driven by a Hydraulic motor, one on every wheel. If you go back a ways in this thread there is quite a bit about the Rolligon company, and some lincs with video of their development.
The Nodwell/Foremost "rig's" have tires up to about 60 inches wide. They are driven in the conventional way using a differential.
Both famlies of vehicles can run on unpacked snow. Both are slow, and run very low air pressure on the tires. In Rolligons, each Airbag has it's own pressure regulator and is maintained at a specific very low inflation pressure. One or more of the linc's on Rolligons shows the interior of the cab with it's array of guages and pressure regulators. The Rolligon's tend to be a bit wider at 14 to 16 feet wide.