The Texas CDL permit (officially the Commercial Learner’s Permit, or CLP) is earned by passing written knowledge tests at Texas DPS. This cheat sheet condenses the highest-frequency facts from the Texas CDL Handbook into a single page. It is a memory aid for review — not a replacement for reading the official handbook, and the examiner and Texas DPS make the final determination on testing and licensing.
Permit Test Logistics
The CLP is made up of separate knowledge tests. You take the General Knowledge test plus any tests that match the vehicle and endorsements you want. Here is the at-a-glance structure:
| Test | Who needs it | Questions | Passing score |
|---|---|---|---|
| General Knowledge | Everyone | 50 | 80% (40 correct) |
| Air Brakes | Driving a vehicle with air brakes | 25 | 80% |
| Combination Vehicles | Class A applicants | 20 | 80% |
Every CDL knowledge test in Texas is scored on the same threshold: you must get 80% correct to pass. On the 50-question General Knowledge test, that means no more than 10 wrong.
As of June 1, 2026, every Texas CDL and CLP knowledge test is given in English only, and interpreters are not permitted. These written tests were previously offered in English and Spanish. The skills test was already conducted in English. Study from the free Texas CDL Handbook on the Texas DPS website.
General Knowledge Must-Knows
Space & Stopping
| Rule | The number |
|---|---|
| Following distance (under 40 mph) | 1 second for every 10 feet of vehicle length |
| Following distance (over 40 mph) | Add 1 extra second |
| Total stopping distance @ 55 mph | Perception (~60 ft) + reaction (~60 ft) + braking (~170 ft) ≈ 290+ ft |
| Empty trucks | Often take longer to stop than loaded ones (less traction) |
| Hydroplaning | Can happen at speeds as low as ~30 mph on wet roads |
Rules & Limits
- BAC limit for CDL holders: 0.04 — half the limit for regular drivers
- Hours of Service (property): 11-hour driving limit, inside a 14-hour on-duty window, after 10 hours off
- Required break: 30-minute break after 8 cumulative hours of driving
- Weekly limits: 60 hours / 7 days or 70 hours / 8 days; reset with 34 hours off
- Cargo inspection: check within the first 50 miles, then every 150 miles or 3 hours (whichever comes first)
- Tiedowns: at least 1 per 10 feet of cargo, with a minimum of 2
Emergencies
- Most skids are caused by driving too fast for conditions
- Drive-wheel (acceleration) skid: stop accelerating and push in the clutch
- Front-wheel skid: the cause is usually too much speed for the turn
- Brake fade: caused by overusing brakes on long grades — use a low gear instead
- Tire fire: never use water on an electrical or gasoline fire; aim the extinguisher at the base
Want to test these before exam day? Run a free practice round.
Take a Practice TestAir Brakes Key Numbers
Air brakes trip up more applicants than any other section because it is all thresholds. Memorize these pressures and the order of the air-brake check:
| What | The number |
|---|---|
| Governor cut-out (compressor stops) | ~125 psi |
| Governor cut-in (compressor restarts) | ~100 psi |
| Low-air warning must activate | Before pressure drops below 60 psi |
| Spring (parking) brakes apply automatically | Around 20–45 psi |
| Pressure build-up (dual system) | 85 to 100 psi within about 45 seconds |
| Static air loss — single vehicle | Less than 2 psi in 1 minute (engine off, brakes released) |
| Static air loss — combination | Less than 3 psi in 1 minute |
| Applied air loss — single / combination | Less than 3 psi / less than 4 psi in 1 minute |
Pick a safe low gear before you start down. Use light, steady brake pressure — do not “fan” (pump) the brakes, which bleeds off air and causes fade.
Combination Vehicles Essentials
Coupling Check (what a locked fifth wheel looks like)
- No space between the upper and lower fifth wheel
- Locking jaws closed around the shank of the kingpin — not the head
- Release arm / safety latch in the locked position
- Landing gear fully raised and crank handle secured
- Air and electrical lines connected, secured, and not dragging
Handling
- Off-tracking: trailer wheels follow a shorter path than the tractor — swing wide enough on turns
- Rearward amplification (“crack the whip”): greatest with doubles and triples — steer gently, avoid sudden moves
- Trailer skid: if the trailer swings out, release the brakes to let the tires regain traction
Top Failure Points (Review These Last)
If you only have ten minutes before you walk in, re-read these — they are the items applicants miss most:
- The 80% passing line and how many you can miss per test
- Following-distance math (1 second per 10 feet, plus 1 over 40 mph)
- The air-brake pressure thresholds — especially 60 psi warning and 20–45 psi spring brakes
- The correct order of the air-brake check
- What a properly locked fifth wheel looks like
- Skid recovery: release the brakes on a trailer skid
Numbers here follow the Texas CDL Handbook, but specifics can change. Always confirm against the current official handbook from Texas DPS, and remember the examiner makes the final call on test day. The two best companions to this sheet are the full Texas CDL permit test guide and a timed practice test.
Frequently Asked Questions
The General Knowledge test has 50 questions, and you need 80% correct to pass — that is 40 right, with no more than 10 wrong. The Air Brakes test has 25 questions and Combination Vehicles has 20, both scored at the same 80% threshold. Confirm current details with Texas DPS before you test.
Focus on the numbers that recur most: the 80% passing line, following distance (1 second per 10 feet of length, plus 1 second over 40 mph), and the air-brake pressure thresholds (low-air warning before 60 psi, spring brakes around 20–45 psi). Those three areas account for a large share of missed questions.
A Texas CLP is valid for 180 days — or until your base driver license or lawful-presence status expires, whichever comes first — and can be renewed one time. You also must hold the CLP for a minimum period before taking the skills test. Confirm the current CLP rules directly with Texas DPS.
No. This is a condensed review aid for facts you have already studied. The official Texas CDL Handbook is the authoritative source, covers material this page does not, and is what the test is written from. Use this sheet for fast review and use the handbook to actually learn the material.
Not always. Everyone takes General Knowledge. You take Combination Vehicles if you are applying for a Class A. You take Air Brakes if your vehicle has air brakes — skipping it adds a restriction that keeps you off air-brake vehicles. See the Texas CDL requirements to confirm which apply to your license class.