Or, you can add an angle to the front of the robot with smaller sprockets on top and bottom, such as
this one for the game where we had to drive up onto the puck.
As important as the treads is where the CG of the robot is; in G'doinkle (shown in the link) we had a minimum speed that we hit the puck in order to have the angular momentum sufficient to overcome the force that was trying to flip the robot backward as we drove up onto the puck. Gary Jones (one of our engineers) actually calculated that speed and we proved his calculations by experiment. Remember that "stairs" is different than "stair" - you not only have to get up on or over one, you have to keep driving at that angle.