How to check if your trailer is secure to your tractor | CDL TEST QUESTION To test if the trailer is secure to the tractor, what should you do? A️⃣ Use the trailer hand valve B️⃣ Pull gently forward in low gear against the locked trailer brakes C️⃣ Check for air leaks D️⃣ Turn off the engine and look under the trailer 💡 Answer: B – Tug test Gently pulling forward in low gear against locked trailer brakes confirms the coupling is secure and the trailer won’t separate while driving. Want to get y