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Calculating inertia for a vehicle robot

I'm trying to set the inertia for this Ackermann vehicle robot. I'm trying to model the GEM e2

I'm using these equations:

It seems pretty straight forward. I'm using meters and kilograms. However, in Gazebo when I use the View Inertia option -- to see the pink rectangles representing the inertia -- it's way bigger than the robot.

Am I missing something important???

Here is how I'm calculating inertia. I've tried it a few different ways:

    <!--<macro name="box_inertia" params="m x y z">
        <inertia  ixx="${m*(z*z+x*x)/12}" ixy = "0" ixz = "0"
                  iyy="${m*(y*y+x*x)/12}" iyz = "0"
                  izz="${m*(y*y+z*z)/12}" /> 
  <macro name="box_inertia" params="x y z mass">
      <inertia ixx="${0.0833333 * mass * (y*y + z*z)}" ixy="0.0" ixz="0.0"
        iyy="${0.0833333 * mass * (x*x + z*z)}" iyz="0.0"
        izz="${0.0833333 * mass * (x*x + y*y)}" />
  <macro name="box_inertia" params="x y z m">
        <inertia  ixx="${m*(y*y+z*z)/12}" ixy = "0" ixz = "0"
                  iyy="${m*(x*x+z*z)/12}" iyz = "0"
                  izz="${m*(x*x+z*z)/12}" /> 
  <macro name="cylinder_inirtia" params="m r h">
    <inertia  ixx="${(m*((3*r*r)+(h*h)))/12}" ixy = "0" ixz = "0"
              iyy="${(m*((3*r*r)+(h*h)))/12}" iyz = "0"
              izz="${(m*r*r)/2}" />

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