Hi and welcome to OSM and the formum

From waht I understood via googletranslate you have to split the way into seperate ways everytime the speedlimit changes. Take a look at https://wiki.openstreetmap.org/wiki/Maxspeed for more information, esp. if there are different maxspeed on the same way (https://wiki.openstreetmap.org/wiki/Maxspeed#Driving_direction).