[BJC]

You will probably want to switch out the outer extension tires to either plaction wheels or pneumatic tires. With only slick wheels on the extensions your robot will act like a giant lever when another robot pushes on it. It will actually make it easier to push/turn you rather than harder.

I don't know exactly how your design works but when your extensions come out are they picking the inner "driving" wheels off the ground? It appears that they are not in which case the above will pretty much be the case no matter what wheels you use.

Really cool design, it has great potential to be "that" robot this year once you work out the tricky spots.

Good Luck!