The bosses of companies have been put before court after vehicles they were using were found to be loading vehicles with too much stock.
The prosecutions were brought by Durham County Council after investigations were carried out into incidents where it found the firms were using "dangerously overloaded" vehicles.
In June, a vehicle belonging to Best Food Supplies Limited, of Mary Street, Sunderland, and being driven by Colin Smedley, 50, of Dacre Road, Fulwell, Sunderland, was checked.
The vehicle, which was carrying cheese and pizza boxes, was found to be 570kg - 16.3% - overloaded.
Another again from June, involved a vehicle belonging to Hartlepool business S&M Bird and Sons, which was found to be transporting bird food.
The vehicle, which was carrying pallets of pigeon corn, was found to be 630kg - 18% - overloaded, with its second axle 440kg - 22% - overloaded.
The cases were head at Newton Aycliffe Magistrates' Court.
Best Food and Smedley were absent from the hearing, but had pleaded guilty by post to one charge each.
Smedley was fined £56 and Best Foods £204.
Both the company and the driver were ordered to pay costs of £200 and victim surcharges of £30.
Partners in S&M Bird and Sons, Thomas Bird, 61, and Ramsey Bird, 57, both of Worsett Lane, Elwick, Hartlepool, each faced two charges in relation to their vehicle.
Thomas Bird attended court and pleaded guilty while Ramsey Bird did not attend and pleaded guilty by post.
Both men were fined £282, ordered to pay costs of £200 and a victim surcharge of £30.
Joanne Waller, the council’s head of environment, health and consumer protection, said: “Overloading a vehicle is extremely dangerous as it puts a massive strain
on tyres, causing them to overheat and wear rapidly – with increased risk of a blowout.
"Overloaded vehicles are also less stable, difficult to steer and take longer to stop.
“By overloading a vehicle you are increasing the chances of it being involved in an accident with potentially fatal consequences.
"This is why it’s so important that we take action against those who overload and I hope these prosecutions and the financial penalties imposed will serve as a deterrent.”