Short answer: do not drive a semi truck on a tire that has gone flat.
A tire that lost air overnight needs an inspection before the truck moves. Driving on it can damage the tire, wheel, or surrounding components, and the correct response depends on what caused the pressure loss.
What to do before moving
Look from a safe position for a visibly deflated tire, sidewall damage, debris, a separated tread, or a wheel concern. Do not crawl under the truck or handle a damaged assembly. If you have a pressure-management system, treat its warning as useful information—not a substitute for inspection.
Parked at a yard
Call fleet maintenance or a mobile commercial tire provider before dispatching the load.
At a truck stop
Give the lot and parking location so a technician can coordinate access.
On a shoulder
Stay clear of traffic and provide the highway direction and nearest marker.
A qualified technician can determine whether the tire is repairable, needs replacement, or has exposed a wheel or mechanical issue. The safest next step is to arrange that assessment before driving.