Huge numbers of agricultural tractor trailer combinations are used for transportation. Many of the combinations rely on over-run braking on trailers. On-road transportation by the combination is being increased by increasing speed and mass capacities due to market pressure. A significant braking safety issue during on-road transportation is dealt with in this work. Proportional integral derivative (PID) control is proposed as a transitional solution towards domination of new tech equipment. Conventional and proposed PID brake controls were compared experimentally by a loaded real world scale agricultural tractor trailer combination. A double axle (front and rear) trailer with 8 tons load was used for dry asphalt road conditions and 0.35 seconds lag time detected between manual and PID controlled braking. Loss of driving stability was reduced by 50% and deceleration increased 21% with PID. Jack-knifing phenomenon is also evaluated. Proposed solution covers an important safety issue and improves braking performance.