Start with mass and volume together
Dense cargo such as steel hits the legal mass limit while the deck still looks empty. Light, bulky cargo such as bales or empty packaging fills the deck long before mass becomes an issue. Work out which one limits you and size the vehicle to that.
Then look at cargo form
Palletised goods suit a tautliner. Craned or oversized items need a flatdeck. Loose bulk needs a tipper. Temperature-controlled cargo needs a reefer. Very heavy or tall machinery needs a lowbed. The form of the cargo usually eliminates most options immediately.
Then check the access
The biggest vehicle is not the cheapest if it cannot get into the yard. Superlinks need serious manoeuvring space. Tri-axles are much easier. Rigid 8 and 14 ton trucks reach urban and restricted sites that trailers cannot.
When in doubt, ask for a recommendation
Send the cargo description, mass, dimensions, pallet count and both addresses. A transport operator can usually specify the vehicle in minutes — and the wrong vehicle on site costs far more than asking.