Home › Practice › Combination Vehicles › Question 64
The forward visibility of a tractor's hood and mirrors creates a blind area in front of the cab of about:
Correct answer: C. 20 feet or more depending on cab height
Why: Tall cabs have a forward blind area of 20 feet or more. Pedestrians, low cars, and bicycles can disappear from view directly ahead of the cab.
Articulated vehicles fail in unique ways: trailer swing under braking, rearward amplification under steering, and jackknife under loss of traction. Combination Vehicle knowledge is required for any Class A applicant under 49 CFR 383.111.
Walk through the coupling sequence verbally until it's second nature. Know the safe-rolling rearward amplification factor, the difference between trailer service brakes and parking brakes, and what creates the conditions for a tractor jackknife.
The Combination Vehicles portion of the CDL knowledge exam covers more than this single question. Use this site's full Combination Vehicles bank to drill every topic, then test yourself with one of our state-specific practice sets to confirm you are ready for the actual DMV exam in your state. Always check your state's CDL handbook for any local addenda before the test day.
If you are still building your overall CDL foundation, start with the General Knowledge bank — every CDL applicant must pass it — and then work outward to the endorsements you plan to add.
