[Pat Hart]

Are you driving in the wide or narrow configuration. If you are driving wide the added distance may allow you to turn without lowering the center wheels. In the narrow configuration you are more likely to need a lower center wheel.

I am not sure how your blocks are mounted but if possible try testing by shimming the middle wheels with washers and find what turns best for your robot. Wheel spacing and center of gravity location can have an effect, so not all robots handle the same way