The maximum width (which is what matters for lane size) of a commercial vehicle (ie real truck or bus) is 102 inches. The largest Suburban tops out at 80 inches. For reference, a Camaro is 74.5 inches. So a Suburban is slightly wider than a car, and a whole lot narrower than a truck.
The maximum height (which is what matters for overpass restrictions) of a commercial vehicle is 168 inches. The maximum height of a Suburban is 74 inches. You could stack 2 Suburbans on top of each other and not be as high as a truck.
Pickups with 4 rear wheels are already classified as medium-duty trucks, and do pay higher tolls and have lane and road restrictions.