[digger48]

In all fairness, they don’t usually take those carts down the road loaded. Those are for field transport.

From the combine to the truck. That way, the combine never has to stop.

Farmers would be more concerned that running loaded on the pavement would be hard on those $4000 tires.

[NVDave]

True, but enough of them find their way onto county roads:

http://www.co.hardin.ia.us/files/AudubonCoIncident.pdf