Understanding your HGV or trailer’s roller brake test report

We represented operators at two recent Public Inquiries in which HGV roller brake test reports became the central issue.

Many operators see their vehicles passing roller brake tests and mistakenly think they do not need to take any further steps – they are wrong!

Firstly, HGV or trailer’s brakes should be tested on a roller brake tester (RBT) at least 4 times per year, including at the MOT. However, best practice is to do them at every PMI and in fact, some Traffic Commissioners are requesting this as an undertaking at hearings.  From April 2025, laden roller brake tests or electronic brake performance monitoring systems (EBPMS) will, with some exceptions, be the only accepted methods for brake testing.

The vehicle must be loaded for a brake test – ideally to at least 65% of its total maximum weight and for each axle to weigh at least 65% of the design axle weight. It can only be tested unladen if it cannot be loaded due to design limitations or the type of load it normally carries.

The roller brake test report will tell you whether the vehicle passed or failed the test. It has 3 sections that include:

  • details about the vehicle being tested
  • information about the brake performance of each axle
  • a summary of the test results for each brake system, showing how the brakes performed during the test (called brake efficiencies)

Operators should use this report to:

  • make sure brakes are in a safe condition
  • identify any problems and carry out repairs
  • keep a printout of the brake test and attach it to the vehicle’s safety inspection record.

Section 1 of the test report provides information about the vehicle.

Section 2 of the test report provides the vehicle’s brake performance by axle.

The report will show the axle weights and the results of checks on the vehicle’s brakes for:

  • bind (only on service brakes)
  • time lag
  • ovality (only on HGV’s steered axles)
  • imbalance
  • max force

The results are ordered by axle and will show the results for the near-side (N/S) and off-side (O/S) readings of the service brake and parking brake. They will also include readings for a secondary brake if the vehicle has an independent control brake system, but not if it’s a split system.


The table shows what is checked during the test and when it will fail.


Check When it will fail
Bind (service brake only) more than 4%
Time lag Manual assessment made
Ovality 70% or higher
Max force less than 5%
Imbalance (service and designated secondary brake only) more than 30%


If the vehicle fails any of these checks, the result will be shown under the ‘Unsatisfactory wheel performance’ header at the bottom of the report.

Designated secondary imbalance is not automatically assessed by the RBT and will be manually entered by an assessor.

Section 3 provides a summary of how the vehicle or trailer has performed during the brake test.


  1. Ensure you have documentary evidence from the maintenance contractor confirming they are carrying out fully laden roller brake test at every PMI. Even if the values are recorded on the PMI sheet, you should always ensure they have provided you with a RBT print out.


  1. Ensure you are analysing the roller brake print out and making further enquiries when necessary.


  1. If you have a transport manager, do not simply assume they are checking the brake test reports – this should be on the agenda at every compliance meeting review with the transport manager so you know the reports are being completed and checked properly. Ensure the regular compliance meetings are documented so you can evidence the checks you have carried out on both the brake test reports and the transport manager.


  1. We urge operators to review the guidance on understanding your brake test reports as it explains when despite a vehicle passing the brake test, further investigations should be made.

Click here to access the government guidance ‘understanding your HGV or trailer’s brake test report.