As advised in May 2026, Main Roads Heavy Vehicle Services has been implementing changes to align with the revised National mass and dimension limits, which come into effect on 1 August 2026.

These changes include:

• Increasing the general mass limits from 16.5t on a tandem axle group and 20t on a tri axle group, to 17t on a tandem axle group and 21.5t on a tri axle group, without the need for Mass Management Accreditation. 
• Allowing 7.0t on a single steer axle with ≥315mm tyres and 11.5t on a twin steer axle group with ≥275mm tyres.
• Increasing the general length limits for certain vehicle combinations from 19m to 20m, including increased rear overhang limits and S-dimension limits, subject to specified requirements. 
• Increasing the tow mass ratio for a rigid truck and tag trailer combination from 1:1 to 1:1.3, subject to minimum steer axle mass requirements.  

As a result, prior to 1 August 2026, all relevant Order and Permit operating conditions will be amended to incorporate these changes. Please refer to the applicable operating conditions for full details of the requirements. 

Important information for operators renewing Modified Mass permits:

Operators renewing permits with Modified Mass, such as Accredited Mass Management Scheme (AMMS) Period Permits, should be aware that the increase to the general mass limits will reduce the amount of Modified Mass required under these permits. Consequently, the permit fee will also be reduced.

If you renew an existing permit, the renewal fee will be based on the fee previously charged for that permit. To ensure you benefit from the reduced permit fee resulting from these changes, you must submit a new permit application through MOVES, or via the online application form, instead of renewing your existing permit.

For further information, please contact the Heavy Vehicle Services Helpdesk on 138 486 or email hvs@mainroads.wa.gov.au .

Heavy Vehicle Services

30 July 2026

Note: This HVS Update will be published until 31 October 2026.