Mecanum Wheel width?

[metainf]

Our team is going to replace the 6" Mecanum Wheels that we have on the robot with the heavy duty set from Andymark http://www.andymark.com/product-p/am-0732.htm. We need to get the width between the wheel plates of the wheels on the robot, but I can't find any information about the wheels that we have on the robot. They are the 6" wheels that Andymark used to sell, but they replaced them with these http://www.andymark.com/product-p/am-0137.htm. Any information, or cad files will be much appreciated