The motorway is closed in both directions between J29 Romford and J30 Dartford as the emergency services fight the blaze.
A huge plume of smoke can be seen for miles around after the fire started around 1pm today (August 13).
Videos show the HGV beside the anticlockwise carriageway engulfed in flame and black smoke caused by the burning tyres.
There have been no injuries, according to Essex Police.
The road is expected by National Highways to be shut throughout the day “due to the nature of the fire” and the likelihood that the road will need resurfacing.
LIVE updates as HGV fire forces M25 to close ‘all day’ from Dartford to Romford
There are delays of at least 60 minutes anticlockwise.
An Essex County Fire and Rescue Service spokesperson said: “We are dealing with a lorry fire on M25, clockwise between junctions 29 and 30.(Image: ECFRS)
“Crews from Grays (two), Basildon, Brentwood and colleagues from London Fire Brigade and Kent Fire and Rescue Service are in attendance.
“The lorry is carrying tyres, which are alight and are producing large amounts of smoke.
“The clockwise carriageway is closed and there are long delays on the anticlockwise carriageway.
“Please avoid the area if you can and take extra care if you are near the scene.”
An Essex Police spokesperson said: “The M25 is closed in both directions between junctions 29 (A127) and 31 (A13), following a lorry fire.
“We are supporting firefighters and National Highways at the scene, and the road is expected to remain closed for several hours.
“Thankfully, no injuries have been reported at the scene.
“Please check before your travel and plan your journeys accordingly.
“Check National Highways for the latest information regarding the road closure and thank you for your patience.”
