Craig 111:
Depends what type of road you’re on, but as a general rule it’s as the stickers on the back indicate: 60, 80, 9060 on secondary routes
80 on main roads where you have ‘priorité’ (indicated by the yellow diamond sign). Often 80 for trucks on two or three lane ring roads i.e Bordeaux rocade, Toulouse périphérique, etc
90 on autoroutes, unless ADR.
Plus 50kph within town/village limits (indicated by the red/white name boards) unless otherwise indicated - can be reduced to 30 for trucks in certain instances
~ Craig
One other thing to look out for, where you see a speed limit of 110 it means that trucks are limited to 80, as I found out once to my cost.