Answer:
Just Under the Heavy Vehicle National Law, road managers have fourteen days to assess a Renewal permit application request. If no response is received by the NHVR at the expiry of this time, the permit can still be issued (expedited).
To avoid any issues with your renewal(s), it is recommended that you submit your renewal application in plenty of time (which is usually 16 days before ahead of its expiry date (at least 16 days but not more than six weeks prior to permit expiry), to allow time for the NHVR to get send your application to the road managers. Note that : If you are able to apply up to six weeks before your permit expires.
Once submitted, your application needs to be with the road managers for a minimum of 14 days, and if no response is received by NHVR the permit can be issued.
If the application to renew a permit within 14 days of the expiry date, you may be without a permit until the renewal is issued.
If an application for renewal is submitted after the expiry date of the permit, the NHVR is unable to expedite renew the application permit and it will be treated like as a new application.