The average of allsubgroups becomes the centerline for the lower plotting area. Average of Ranges Example Step 7 - Calculate the upper control limit (UCL) and lower control limit (LCL)for the averages of the subgroups. At this point, your chart will look like aRun Chart. Now, however, the uniqueness of the Control Chart becomes evidentas you calculate the control limits.
Ford Motor Company recommends that the Crown Vic limit its towing to a trailer with a gross vehicle weight of 1500 lbs or less with a tongue weight not to exceed 150 lbs. See HERE.
That model can also haul up to 5,817 pounds in the bed. The best model for conventional towing would be the same truck but in the Crew Cab body style. That model can tow up to 19,600 pounds or a still impressive 22,600 pounds with a fifth wheel. Payload is rated 5,205 pounds.