Help Using Xbox Wireless Steering Wheel for Need for Speed Shift?

What buttons on the xbox wireless steering wheel control the buttons 'LB' and 'RB'? I'm a little confused…since the steering wheel has only 9 controls and controls 'LT' and 'RT' just fine, but there is no evidence from what I've seen that it controls the buttons next to them.

Suggestion:

Don't know.