Description about Tractor with trailers in traffic for DLC France v3.4 [1.27.x]:
New version 3.4
Harvester now have beacon lights (thanks to Todor Alin)
Tractors now work from 5:00 till 21:00 (thanks to Drive Safely for Guide )
Tractors not spawned in cities (added traffic_rule.sii file)
But they can spawn on expressway.
Default harvester have own sound.
Reduced traffic appear frequency as much as possible, because spawn_ratio not work properly, here used another trick.
Tractor and harverster added to "slow" vehicle type, so, sometime, you can see 2 tractors at once.