I disagree. The latest highway code shows the legal speed limit for HGVs as being 60 mph - http://www.highwaycode.gov.uk/09.shtml#103
Likewise the legal speed limit for coaches on the same motorway is 70 mph.
But the new digital tachographs will note any HGV being driven at over 90 km/h for over 1 minute, whereas for coaches only when the speed exceeds 105km/h for one minute will an offence be recorded.
True Neil & its only the foolish few, or those who have a genuine limiter fault who do.
I know of one reputable operator that has a unit that seems to eats limiters, I also feel that this thread is interesting when compared to the one on overtaking where everyone is discussing the problems of us all doing the same speed & not how to avoid doing so.
when i first passed my class 1 back in the mid eighties i was still in the RAF. we had a couple of seddon 411,s and a cuople of them horrid iveco/ford cargo things 
.
themdays i used to drive them on the motorways at a steady 65 to 70 mph. there was no cutting up or endless 7 mile overtakes. it was great,
well what did i know i was only 20.
i did get a pull though once when bobtailing in scotland near stranraer, i was doing 55 on a single carriageway and i got pulled by a panda.
the policeman said i should be doing forty but like a **** i said "its under 7 1/2 ton ( which it was) and that that speed limit did not apply to me.
well wether is was my lie or the fact that it was a military truck got me off, in fact the poor old policeman lookeD so confused.
its a good job it wasnt a traffic cop as knowing me i still would have waffled and no doubt got nicked.
anyhow it was a year later, still very young and full of it i set off for south wales in a cargo thingy loades with a couple of aero engines and a very big genarator and i was going downhill near ross on the a50 and i had the heap off the clock 
, a car pulled out on me so i dabbed the brakes as you do and at the speed the truck didnt react as fast as id have liked. i had no option to pass the car and scare the [zb] out of me and him.
MAJOR LESSON LEARNT THAT DAY.
and it wasnt all car drivers are berks 
Small one.L.
just like atra if its doing over 56 for over 2 mins it’s dragged into the office for a verbal/then written and then its up the road.
paid by the hour no silly delivery windows so no rush.
jon
point is the limit on the motorway is 60 mph with limiters set at 56 mph dictated by the europeans like everything else, was some one lying to me at school or did we really win two world wars to be free of that sort of thing 
years ago (1986/7)
I had a White Roadcommander2 with a cat 400 engine
It would do 90 mph the only trouble was stopping it it!!!
at least the electric jake brake worked !
Ha Ha
The short answer is…as fast as she’ll go!
I usually let it get up to about 70mph downhill, and before I get the ROSPA mob going on about how HGV’s aren’t safe at that speed, let’s not forget Munchman in the States, where it is legal to drive an artic at 75.
I’ve had a top whack of 85 as well when I was younger. I wasn’t being brave or clever, just young and boisterous.
The law is the law and if I got caught I’d have no-one else to blame, but the question was asked, I’ve given my answer.
Dazza
Speed Limiters - Must be fitted and maintained in good order. Vehicle limiter plates should be displayed in a prominent position. Limiters must be fitted to all vehicles above 12 tonnes registered after 1st January 1988.
VOSA are checking speed limiters at roadside checks. One of are drivers and the firm where prosecuted THE DRIVER lost his vocatonal Licence for 3 mounths plus a hefty fine. beware If the vehicle is exeeding 56mph (90km/h) limiter on the flat.( not down hill) defect it. and save your licence and keep your money in your pocket. Not hand it over to a court to pay a fine.
mcpartland:
Speed Limiters - Must be fitted and maintained in good order. Vehicle limiter plates should be displayed in a prominent position. Limiters must be fitted to all vehicles above 12 tonnes registered after 1st January 1988.
VOSA are checking speed limiters at roadside checks. One of are drivers and the firm where prosecuted THE DRIVER lost his vocatonal Licence for 3 mounths plus a hefty fine. beware If the vehicle is exeeding 56mph (90km/h) limiter on the flat.( not down hill) defect it. and save your licence and keep your money in your pocket. Not hand it over to a court to pay a fine.
The weight limit is 7.5 tons and above for the 90 km/h speed limiter. Vehicles that had a 60 mph speed limiter (between 7.5 and 12 tons) will need to be set at 90 km/h (56 mph) from 2005. In fact the new rules from 2005 say all vehicles > 3.5 tons have speed limiters - 90 km/h for goods vehicles and 100 km/h for passenger vehicles with more than 8 seats.
during discussion with personel at recent highways exhibition when asked question of regular checks and calibration on test equipment used by ministry they said the equipment was accurate to + - 2% but no regular checking was done and they advised no prosecutions if offence was within 4% so its worthwhile arguing your case. But theyll definitly get you next time.