Ontario · Written knowledge test
Ontario DZ
Practice Test
Prepare for your Ontario Class D and Z air brake knowledge tests with free practice questions and clear explanations. Review commercial driving rules, road signs and air brake systems, then identify where you need more practice.
Free account · No credit card required
Explore sample questionsAt a glance
- Subjects
- Class D + Z Air Brakes
- Samples
- No account required
- Free tests
- 20 Class D + 20 Air Brake questions
- Paid access
- 365 days · One-time payment
01Try it free
Sample questions
Try these sample questions without an account. Create a free account for a 20-question Class D test and a 20-question Air Brake test, both with answer explanations.
An ordinary truck has a gross weight of 12,000 kg and no trailer. What licence authority is needed for its weight, assuming all other requirements are met?
At a glance
- Subjects
- Class D + Z Air Brakes
- Samples
- No account required
- Free tests
- 20 Class D + 20 Air Brake questions
- Paid access
- 365 days · One-time payment
02The licence
What Is an Ontario DZ Licence?
Class D: the vehicle licence
Class D permits trucks over 11,000 kg gross or registered gross weight, including qualifying combinations where the towed vehicle does not exceed 4,600 kg. Heavier trailers require the appropriate Class A licence.
Z: the air brake endorsement
Z is an endorsement, not a separate vehicle licence class. It is required to drive vehicles equipped with air brakes. A Class D driver needs Z when the truck has air brakes; D and Z together are commonly called DZ.
Two subjects, one preparation plan
Class D preparation focuses on commercial driving rules, signs and vehicle safety. Z preparation focuses on air brake systems and checks. Knowledge practice is only one part of licensing: eligibility, vision and medical requirements, road testing and air brake practical requirements must also be met.
03The curriculum
What Does DZ Preparation Cover?
Class D · Road rules & vehicle safety
Commercial driving rules
Right-of-way, following distance, stopping, railway crossings and safe truck operation.
Road signs, signals & markings
Regulatory and warning signs, traffic lights, pavement markings and temporary road conditions.
Truck safety & inspections
Vehicle weights, load security, daily inspections, defects and safe-driving decisions.
Air Brakes · Systems & checks
Air supply & pressure control
Compressors, reservoirs, governors, cut-in and cut-out pressure, gauges and low-air warnings.
Service & spring brakes
Brake chambers, brake application and release, parking brakes and spring-brake operation.
Adjustment & system checks
Slack adjusters, pushrod stroke, air loss and the sequence of pre-trip air brake checks.
04Test day
What to Expect on Ontario Knowledge Tests
Official knowledge tests
DriveTest describes knowledge tests as multiple choice, available on paper and at some locations on computer. They are not timed. DriveTest states that a total score of at least 80% is required to pass. Check the current requirements for your licence and endorsement before attending. Our practice-test length and timer are not the official test format.
Study the official handbooks
Use the Official MTO Truck Handbook for Class D and the Official MTO Air Brake Handbook for Z. Review the Driver’s Handbook for road signs and general road rules. Practice questions support these materials; they do not replace them.
Written knowledge is not a road or practical test
Class D road testing assesses daily inspection, backing and on-road driving. The Z endorsement also has practical requirements. Ontario provides approved air brake course and DriveTest testing pathways; confirm which pathway applies to you before booking.
05Your preparation
How to Prepare for Your D and Z Tests
- 01
Study the official handbooks
Read the Truck and Air Brake handbooks, with the Driver’s Handbook for signs and general road rules.
- 02
Take the free practice tests
Create a free account and try Class D and Air Brakes separately to establish a starting point.
- 03
Review the explanations
Understand why an answer is correct and revisit the relevant handbook section when a rule is unclear.
- 04
Practise your weak topics
Repeat the areas you find difficult. The paid pass adds more practice sets; continue hands-on preparation separately.
06Choose your practice
Samples, Free Tests & the DZ Pass
No-account samples
Answer the sample questions above and read their explanations without signing up. Switch subjects to try Class D or Air Brakes.
Free-account practice
A free account includes a 20-question Class D test and a 20-question Air Brake test, with answer explanations. No credit card required.
Paid DZ practice
Unlock 22 Ontario DZ practice sets covering Class D and Air Brakes. Practise at your own pace or use timed exam mode, review clear answer explanations and save your results for 365 days. Class D-only and Air Brake-only passes cover the selected subject.
07Your next step
Pricing
One-time payment
Complete Ontario DZ Pass
Class D written + Z Air Brake. 12 months access.
$39CAD
Try a free 20-question practice test before you buy.
08Before you start
Frequently asked questions
For Commercial Truck Drivers in Ontario
Whether you're pursuing a career in trucking, construction, municipal services or other commercial driving roles, an Ontario Class D licence with a Z air brake endorsement can open the door to new opportunities. Prepare for your written knowledge tests with realistic practice questions covering commercial driving rules, road signs, vehicle safety and air brake systems.
10Reference material