Many steel wheels found on 1 ton pick up trucks have larger center holes. For good balancing result, the wheel must be mounted properly on the wheel balancer with the suitable sized cone and spacer. This truck adapter kit is needed to properly center wheels with larger than normal center holes. The large truck adapter kit comes complete with a large 2-sided cone (4.75"-6.875" 120-175 mm), and a spacer/backing hub diameter expansion (7.4"-8.625" 188-223 mm). The spacer/backing hub diameter expansion is used to "push" the wheel away from the machine, so that the tire does not contact the machine during the wheel spinning. Also the spacer can expand hub diameter so the rim can be locked properly on the shaft. This kit fits all 36 mm diameter Shaft Wheel Balancers. Experience more reliable and repeatable truck wheel mounting. Increased ease of use.