Which version of pak128 do you play then?
In recent pak128 versions (release as well as the nightlies), there's a truck-trailer that can carry 35 tons of steel at 100km/h - and before that one is introduced, there is one available for 28 tons which is capable of 90 km/h. So "only one for 75 km/h" is not exactly true.
Agreed, even these cannot drive on the 110km/h minimum roads created by the new signs, so maybe we should set these signs down to 100 km/h or so - that should allow all types of goods to be transported again. Actually I think these signs were orignally both made for 80 km/h, just with the modern version being lighted at night. Apparently this was later changed to a higher speed, maybe without checking the top speeds for all goods' vehicles... (VS, any idea on how to solve this?)
On the other hand, there still is a minimum 80 sign available throughout timeline (or well from 1950 onwards, to be precise), so if 110km/h is too fast for you, you could always just build these signs with a normal one-way sign instead...
But we'll look into it. Maybe it's not the trailers that are causing the problems but the trucks pulling them (there are quite a few fast enough for the job, but it seems - after a short look - that they might all be introduced later than the modern signs...) Yes, some things there certainly need to be checked...