Here is the full list of all 19 Heavy Duty Challenge: The Off-Road Truck Simulator achievements.
Buy all 12 trucks
Win a platinum Event trophy with a four-axle truck
Fully upgrade a truck
Fully reinforce a truck
Buy a truck reinforcement
Buy a truck upgrade
Win a platinum Event trophy with a three-axle truck
Buy a two-axle truck
Buy a three-axle truck
Buy a four-axle truck
Complete your first Event outside of Driving School
Complete your first Championship
Win a platinum Championship trophy
Win a platinum Event trophy with a two-axle truck
Complete your first Section outside of Driving School
Finish a section with the highest possible score
Complete Driving School
Complete all Events in the same truck
End a section by crashing your truck