When I was running I-90 from Boston to several stops in Ohio and IN there is a stretch of that road that runs alongside Lake Erie in PA where there's nothing to break the wind between the road and Canada. Frito Lay trucks often had to get alongside a van or reefer to get past that stretch to avoid being blown over. So even if you cram every bag possible into one of those drop floor vans it's still not going to weigh very much. After all, the biggest thing in the bag of chips, by volume, is air.