Well this might be stupid to post but maybe not. What is the fastest truck you have driven? Make, Model,Year? I know it should be 56mph, for the rest of Europe i think its 53mph. But not all are set at that speed. So if you were lucky and drove a truck that wasnt set. Let me know. This could be fun 
i did drive a rigid with a dodgey limiter once but i only took it up to 60 and i reported it when i got back which did not make me popular with the full time drivers 
I drove an F10 wag & dragon about 6 years ago ( It wasn’t mine, I was just doing night abattoir runs a couple of nights a week) driving down a very empty M5 glanced down - oops 70mph 
I drove a DAF 1900 for Unigate on store deliveries a few years back that could do errr ummmm
Well you had to pull over to put the needle back on the card because it would go off the top then get caught on the edge of the card on the way back down
Alledgedly
I had a MAN rigid on hire and had it up to 75 mph.
was driving down the A64 towards leeds an was overtaking every in sight ( except the reps ) looked down at the speedo and realised my speed.
put a defect in when i got back to the yard but do not know if it was looked at because i never drove it again.
Had a jreg leyland artic a year back, so it had no speed limiter, it would crack 70.
ralliesport:
Had a jreg leyland artic a year back, so it had no speed limiter, it would crack 70.
I’m pretty sure speed limiters came in in about 1987 (C/D reg) so it should’ve had one fitted
I had a Bedford TK ( Flatbed Rigid ) that would do 75 easy and then you had to hold it back - I kid you not. I also had a DAF 1900 Flatbed Rigid, fantastic motor, less than a year old, F- Reg 89 I think, no limiters back then. It would do 85 allegedly. and 17 mpg. 
Limiters were only required to be fitted on vehicles from G Reg onwards 
plenty of lorries would do 70+ if loaded heavy and going down a steep hill if youve got the nerve to take em out of stick and hang on.
gardners were goverened of course, and if tyou let the engine overrun the governor, you was risking dropping a valve a few colleugues fell foul of this with 240’s, so it was out of stick with them.
the buffalo would wind up to 70+, and almost anything with a 290 â– â– â– â– â– â– â– i reckon, anyone with a good memery remember how fast a 290 would go? i seem to remember down a hill you could do the clock on a tacho.
but the genuinely fastest motor i ever had was the merc 1748, all you had to do was unplug a big block with about 30 wires in it located under the passeneger side dash, and it was a flyer, it didnt need a hill to pull the clock loaded, but you had to be carefull of tyers at that type of speed and the fuel was pretty bad too. as i was paying the bills i didnt do too much of it!
In 1971, also a Bedford TK flat, carrying cardboard cartons, reached 78 mph. In '74 I got 75 out of another rigid, a D-Series Ford on the A1 at Welwyn. The AEC Mandators could be wound up, usually with a cab-high trailer load. This was when flat bodied lorries were very common, there was an aerodynamic advantage to them, in that the vehicle envelope was only as high as the load, and did not always have a flat, high back end, which causes a lot of drag, and they weren’t carrying the weight of bodywork and doors, just sheets.
wouldnt no but it was around the 2100 rpm in a 420 topline scania
Drove a V8 Scania with a blown fuse once !!! Went past everything
north surrey haulage:
ralliesport:
Had a jreg leyland artic a year back, so it had no speed limiter, it would crack 70.I’m pretty sure speed limiters came in in about 1987 (C/D reg) so it should’ve had one fitted
1/1/88 for vehicles over 12 tonnes
I know this cos my old E reg F10 was first registered 7/1/88
(and it says so in the RHA haulage Manual 2005)
rules are different for 7.5t+ to 12 t vehicles
more than the clock read anyway … 
Our Scania until recently had the limiter set to 60, although it’s been reset to 56 since it’s inspection. That worked a treat on the motorway, the extra 4mph let you get past all but the irish lorries and legaly!
gardners were goverened of course, and if tyou let the engine overrun the governor, you was risking dropping a valve a few colleugues fell foul of this with 240’s, so it was out of stick with them.
the buffalo would wind up to 70+, and almost anything with a 290 â– â– â– â– â– â– â– i reckon, anyone with a good memery remember how fast a 290 would go?
Totally depends on the gear ratios, so to say an ‘engine’ will do a certain MPH isnt really acurate. As i understand it race trucks have higher gear ratios (they pull no weight) so that at the same revs they go faster.
I wasn’t driving but got blown over by a Peterbilt coming up the M1 today
DAF 2800DKSE (the E was the important bit )
Wetherby bypass when it was being built: I got a police car with blues behind me. He kept flashing me so I formed the opinion he wanted me out of the way and being only 1 lane then I took the chance and floored it for him. Don’t know what the speed was but it was off the clock and I still had 300rpm to go to the red band!
ive let them go downhill before at to 75 but that was on nights on job and knock…
and no i didnt have a 45 off when i should have…
Last summer in a P-reg Volvo FL7 rigid that I realised had a knackered limited when I looked down to see I was doing 67mph along the M180 one saturday afternoon. I slowed back down to just under 60 but at 67 it showed absoluetly no signs of slowing off with eceleration and would probably of gone quite a bit faster, not bad for a truck of that age that has probably been thrashed hard all its life and was fully loaded at the time and it wasn’t downhill either.