Wheels for drivetrain

[jon-s]

We currently are using mecanum wheels for our drivetrain but need more traction to climb onto the bridge. Our chassis is too stiff for the mecanum wheels to work properly, and limits us to 8in wheels. We also need to be able to make the change(s) in the practice day of competition.

We are considering changing to either the FIRST wheels (http://www.andymark.com/product-p/am-0420.htm) or the Plaction wheels (http://www.andymark.com/Plaction-s/103.htm). Which of these wheels do you guys recommend or would you suggest a different type of wheel?