Missouri CDL General Knowledge Practice Test 2025

Missouri is the only state where the Department of Revenue (DOR) issues driver's licenses and CDLs. This structure dates to Missouri's historical administrative organization — driver licensing was assigned to DOR as part of a broader revenue collection and identification function. All other states use agencies titled DMV, BMV, MVD, SOS, DPS, or similar. For CDL applicants, the DOR functions identically to any other state motor vehicle agency — the administrative difference is in name only.

The Missouri CDL General Knowledge test has 50 questions. You need 40 correct (80%) to pass. Missouri also requires endorsement tests for HazMat (30 questions), Tanker (30 questions), Passenger (20 questions), School Bus (20 questions), Doubles/Triples (20 questions), and Air Brakes (25 questions). Each endorsement test requires 80% to pass.

Missouri CDL holders in a commercial motor vehicle face the federal 0.04% BAC standard — Missouri calls it DWI rather than DUI but the threshold is identical to federal FMCSA requirements. A DWI conviction in any vehicle (including a personal car) triggers FMCSA CDL disqualification: 1 year for first offense, lifetime for second. Missouri DOR reports convictions to FMCSA within 10 days.

Missouri's Ozark region has numerous low-water crossings used by freight vehicles on county and state routes. Flash flooding — which can occur within minutes of heavy rain upstream, even on a clear-day road — closes these crossings and can trap vehicles. CDL drivers should: (1) plan alternate routes before entering Ozark regions in rain season (spring, fall); (2) monitor MODOT Traveler Information (1-888-275-6636 or modot.org); (3) never drive through a barricaded flood crossing under RSMo 304.022. The Mississippi River and Missouri River corridors also affect freight routing during annual spring flood events.

Missouri CDL skills tests (pre-trip inspection, basic vehicle control, on-road driving) are administered at DOR-approved Third Party Tester (TPT) locations. TPT sites must use FMCSA-standardized test routes and scoring. Knowledge tests are available at DOR driver license offices statewide. Missouri has TPT sites in Kansas City, St. Louis, Springfield, Columbia, Joplin, and other cities.

A Class A CDL allows you to operate any combination of vehicles with a Gross Vehicle Weight Rating (GVWR) of 26,001 lbs or more, provided the towed unit exceeds 10,000 lbs — this includes tractor-trailers and double/triple trailer rigs. A Class B CDL covers single vehicles with a GVWR of 26,001 lbs or more, or any such vehicle towing a unit not exceeding 10,000 lbs — this includes straight trucks and large buses. A Class C CDL is required for vehicles designed to carry 16 or more passengers (including the driver) or for vehicles transporting hazardous materials that require placarding, when those vehicles do not qualify for Class A or B.

CDL fees vary by state and by the class and endorsements you obtain. Most states charge separate fees for the CDL knowledge test ($10–$30 per attempt), the CDL skills test ($50–$150), and the CDL license itself ($50–$100). Additional fees apply for each endorsement (HazMat, Tanker, Passenger, etc.). The HazMat endorsement also requires a TSA security threat assessment fee of approximately $86. Check your Missouri DMV website for current fee schedules.

Federal regulations (49 CFR 383.133) require that CDL applicants be able to read and speak the English language sufficiently to understand highway traffic signs and signals and to respond to official inquiries. Many states offer CDL knowledge tests in Spanish and other languages for non-commercial knowledge questions, but the actual CDL test must be taken in a language that allows the driver to meet the English proficiency requirement. Check with the Missouri DMV for available language options.

In most states, a CDL is valid for 4–8 years (commonly 4–5 years). To renew your Missouri CDL, you typically need to visit a DMV office, pass a vision test, pay the renewal fee, and update your medical certification (DOT physical). If you hold a HazMat endorsement, your TSA background check must also be current. CDLs cannot generally be renewed online due to federal requirements for in-person verification of medical certification.

If you fail the CDL General Knowledge test in Missouri, you are typically required to wait a specified period (commonly 1–7 days) before retaking it. Most states allow 2–3 attempts before requiring additional waiting periods or study requirements. There is usually a retest fee for each attempt. Focus on the areas you missed — most states provide a score sheet showing which topic areas you need to review.