Chevrolet 2009 Express Owner's Manual page 312

Dual Rear Wheels
If the vehicle has dual rear wheels and the tread
design for the front tires is the same as the
rear tires, always use one of the correct rotation
patterns shown here when rotating the tires.
5-72
If the vehicle has dual rear wheels and the tread
design for the front tires is different from the dual
rear tires, always use the correct rotation pattern
shown here when rotating the tires. The dual tires
are rotated as a pair and the inside rear tires
become the outside rear tires.
When you install dual wheels, be sure that vent
holes in the inner and outer wheels on each
side are lined up.
Also see Dual Tire Operation on page 5-65 for
additional information.