CDL combination vehicles
Every commercial driver starts with the general knowledge test. It covers the federal rules drivers live by (hours of service, inspections, disqualifications), vehicle control, space and speed management, hazards, emergencies, cargo and railroad crossings.
Federal law requires a commercial driver's license to drive a commercial motor vehicle, and every CDL applicant must pass the general knowledge test first. 49 CFR 383.23 (Commercial driver's license required) and 383.111 (Required knowledge).
Practice and timed mocks are free, with right or wrong on every answer and your total score. The full analysis is $39, once.
How the exam is built
Owned by Federal Motor Carrier Safety Administration (standards); state licensing agencies (tests).
Combination vehicles
20 scored questions, to pass: 80% of scored questions right.
| Topic | Share |
|---|---|
| Combination Vehicles (49 CFR 383.111(c)) | 100% |
The official outline: www.ecfr.gov/api/renderer/v1/content/enhanced/current/title-49?part=383&subpart=G. Checked 2026-10-08.
Sources
- FMCSA required knowledge for CDL endorsement and restriction-removal tests: 49 CFR 383.111(b) air brakes, 383.111(c) combination vehicles, 383.115 doubles/triples, 383.117 passenger, 383.119 tank, 383.121 hazardous materials, 383.123 school bus (eCFR, current as of retrieval), retrieved 2026-10-08.
- 49 CFR 383.135 (passing knowledge tests: 80 percent), retrieved 2026-10-07.
Questions are original, written from the official outline and primary sources under an assessment framework designed by Julian Calvo, Ed.D., M.S. DecipherU is not affiliated with FMCSA or any state licensing agency. Every practice question is original and written from federal regulations and official state CDL manuals.