To determine the dual spacing dimension of two disc wheels or demountable rims, add their offsets; for rims, also add spacer width (see diagrams).  The clearance between tires may be calculated by subtracting the width of one tire section from the dual spacing dimension.  The tire section width dimension may be obtained by referring to the tire manufacturer’s data book.  The wheel/rim offset dimension is given in the wheel/tire and rim application tables in this section.

It should be noted that the outside dual wheel’s offset and rim width directly affects the overall width of the vehicle’s running gear (one side to the other).  Maximum overall width is set by state and federal law.  Inboard clearance to vehicle is directly affected by the inner dual wheel rim width and offset.  See Tire/Rim Size Selection page for tire section width and wheel offset information.

Tubeless and tube-type rims are interchangeable on the same cast spoke wheel.  Inside rim diameters are identical for all rims listed.

Caution is necessary in selecting wheel/rim offsets to insure proper tire spacing, body and chassis clearance, and overall width.  If dualing is involved, minimum dual spacing must be provided as shown to give proper clearance between tires.  Minimum dual spacing data is shown with approved rim and tire combinations.