Spec Smart: Don’t know your gear split chart from your rear axle ratio? Read our primer on medium-duty truck spec’ing. by trucknews.com December 22, 2006. You run a handful of medium-duty trucks to ...

Vehicle speed (mph), engine speed (rpm), tire diameter (inches), trans gear ratio, and rear axle gear ratio are all interrelated. If you know four out of five of these values, you can determine ...

The "crawler" gear ratio—with the 5.575 "working gear" included—is 55.874, the rear axle ratio is 2.182, and the hub ratio (remember, this thing's got portal axles), is 2.714.