Grade 10 power mechanics – Road Wheels Quiz

1. What is the primary function of a vehicle's road wheel?

To cool the engine by drawing air through the radiator
To store fuel for long journeys
To change gear ratios for different speeds
To support the vehicle and allow it to roll on the road
Explanation:

Road wheels carry the vehicle's weight and provide a rolling surface so the vehicle can move along the road.

2. Which part of the wheel holds and seals the tyre to the rim on modern cars?

Wheel nut
Spoke
Bead
Hub cap
Explanation:

The tyre bead is the reinforced edge of the tyre that sits against the rim flange and creates an airtight seal for tubeless tyres.

3. What does the tyre marking '195/65 R15' tell you?

Tyre pressure must be 195 kPa at 65 degrees temperature and rim 15 cm
Tyre compound is type 195, manufactured by company 65, in region 15
Tyre width is 195 mm, aspect ratio 65%, and fits a 15-inch rim
Tyre can carry 195 kg and was made in 1965 on the 15th day
Explanation:

Tyre codes show width in millimetres, aspect ratio as a percentage of width, and rim diameter in inches (R for radial).

4. Which tyre type is most common on modern Kenyan passenger cars?

Airless foam tyre
Solid rubber tyre
Bias-ply tyre
Radial tyre
Explanation:

Radial tyres are widely used for passenger cars because they give better grip, fuel economy and ride comfort compared with bias-ply tyres.

5. What is the main danger of driving with under-inflated tyres?

Improved fuel economy and longer tyre life
Increased tyre wear and risk of tyre overheating or blowout
Guaranteed better traction on dry roads
Automatic repair of small punctures
Explanation:

Under-inflation increases the tyre's contact area and flexing, causing higher wear, heating and possible tyre failure.

6. Why is wheel balancing important?

To keep the brake pads cool during braking
To increase the vehicle's top speed
To reduce engine oil consumption
To prevent vibration and uneven tyre wear at speed
Explanation:

Balancing ensures mass is evenly distributed so wheels do not vibrate, improving comfort and tyre life.

7. What does wheel alignment adjust?

The engine idle speed
The wheel nut torque only
The tyre chemical composition
Camber, caster and toe angles of the wheels
Explanation:

Alignment sets the wheel angles (camber, caster, toe) so tyres contact the road correctly and wear evenly.

8. Which of these indicates positive camber?

The wheel rotates inside the hub
The wheel moves backward under acceleration
The top of the wheel tilts inward toward the vehicle
The top of the wheel tilts outward from the vehicle
Explanation:

Positive camber is when the top of the wheel leans away from the vehicle centreline.

9. What does 'toe-in' mean in wheel alignment terms?

The wheel hub has worn bearings
Tyres are fitted without inner tubes
Front edges of the tyres point slightly toward each other
Wheels are out of balance and need weights
Explanation:

Toe-in refers to wheels pointing slightly toward each other at the front, affecting steering stability and tyre wear.

10. How often should tyres be rotated to extend tyre life on a typical family car?

Only when a puncture occurs
Never; rotating tyres shortens life
Every time you refuel
About every 8,000 to 12,000 km (5,000 to 8,000 miles)
Explanation:

Regular tyre rotation evens wear among tyres; manufacturers commonly recommend rotation every 8,000–12,000 km.

11. What is the correct first step before removing a wheel from a parked vehicle?

Deflate the tyre completely
Remove all tyres from the vehicle
Apply the parking brake and chock the opposite wheels
Start the engine to use power steering
Explanation:

You must secure the vehicle by setting the parking brake and placing wheel chocks to prevent rolling before jacking and removing a wheel.

12. What tool is normally used to loosen wheel nuts before lifting the vehicle?

Wheel wrench (lug wrench)
Screwdriver
Oil filter wrench
Hammer
Explanation:

A wheel or lug wrench provides the leverage to loosen tight wheel nuts safely before raising the vehicle on a jack.

13. Which wheel component allows the wheel to rotate smoothly around the axle?

Wheel bearing
Tyre tread
Wheel nut
Valve stem
Explanation:

Wheel bearings are rolling element assemblies that support the wheel and allow smooth rotation with minimal friction.

14. What is the main advantage of tubeless tyres over tube-type tyres?

They are less likely to blow out suddenly and can be repaired more easily
They never get punctures
They do not require air pressure
They are always cheaper
Explanation:

Tubeless tyres hold air at the bead and often seal small punctures, reducing sudden blowouts and simplifying repairs compared with tube tyres.

15. Why should wheel nuts be tightened in a star (criss-cross) pattern when fitting a wheel?

To make the nuts easier to remove later
To increase brake pad life
To decorate the wheel with a star pattern
To ensure the wheel seats evenly against the hub and avoids warping
Explanation:

Tightening in a criss-cross pattern draws the wheel onto the hub evenly, preventing misalignment or damage to the wheel or brake disc.

16. What tyre tread pattern is best for wet roads to reduce risk of aquaplaning?

Small knobby treads meant only for off-road use
Metal studs embedded in the tread
Completely smooth tyres with no grooves
Deep grooves that channel water away from the contact patch
Explanation:

Grooves and sipes help move water away from under the tyre so the rubber keeps contact with the road, reducing aquaplaning.

17. How can worn wheel bearings commonly be identified while driving?

By a constant humming or grinding noise that changes with speed
By a sudden loss of tyre pressure
By increased fuel consumption only at idle
By the horn sounding different
Explanation:

Worn bearings often make a rumbling, humming or grinding noise that varies with road speed and can indicate bearing failure.

18. What should you do immediately if you get a tyre puncture on a Kenyan road and cannot change the wheel safely?

Keep driving fast to reach the nearest town quickly
Slow down gradually, pull onto the hard shoulder or safe spot and switch on hazard lights
Remove all load from the vehicle and continue at the same speed
Stop in the middle of the road and leave the vehicle
Explanation:

Reducing speed, moving to a safe place and warning other road users keeps you safe until you can repair or change the tyre.

19. What does the speed rating letter on a tyre indicate?

The year the tyre was manufactured
The tyre's colour
The maximum safe speed the tyre can handle
The amount of air needed in kPa
Explanation:

Tyre speed ratings are letters that show the maximum speed a tyre is certified to carry a specified load safely.

20. Why must replacement wheels match the vehicle's bolt pattern and offset?

To ensure the wheel fits the hub correctly and does not cause steering or clearance problems
To make the brakes last forever
To stop the battery from discharging
So the wheel will change the engine power
Explanation:

Bolt pattern and offset affect how the wheel mounts and its position; incorrect fit can cause rubbing, steering issues or unsafe load on bearings.

21. What is the recommended action for tyres that have tread depth below the legal or safe limit?

Only rotate them and keep using
Paint the tread to hide the wear
Replace the tyres immediately
Drive faster to reduce wear evenly
Explanation:

Tyres below the safe tread depth reduce grip, especially on wet roads, and should be replaced to maintain safety.

22. Which valve type is most common on car wheels for inflating and checking tyre pressure?

Dunlop valve
Presta valve
No valve β€” tyres self-inflate
Schrader valve
Explanation:

Schrader valves are the common, sturdy valve types found on most car tyres and accept standard air pumps and gauges.

23. What causes uneven tyre wear on the inner or outer edge of a tyre?

Not changing the wiper blades
Washing the car too often
Incorrect wheel alignment such as wrong camber or toe settings
Using high octane petrol instead of diesel
Explanation:

Misaligned camber or toe angles make the tyre contact uneven, leading to excessive wear on one edge.

24. When repairing a small puncture in a tubeless tyre, what is the common safe repair method at a workshop?

Welding the rubber closed
Plugging and patching from the inside (combination repair) by a trained technician
Taping the outside of the tyre with duct tape
Pouring oil into the tyre to seal the hole
Explanation:

A proper repair combines an internal patch with an external plug and must be done correctly to restore tyre safety; roadside quick fixes are unsafe.

25. What effect does over-inflation of a tyre have on vehicle handling and tyre wear?

It permanently increases tyre size without consequences
It makes the vehicle float and improves cornering permanently
It guarantees better fuel economy always
It reduces the contact patch causing harsher ride and greater centre tread wear
Explanation:

Over-inflation makes the tyre bulge at the centre, reducing grip, making the ride firmer and causing the centre of the tread to wear faster.

26. What is the primary function of a vehicle's road wheels?

Control the vehicle's steering electronics
Cool the engine by moving air
Support the vehicle's weight and transmit driving force to the road
Store electrical energy for the vehicle
Explanation:

Road wheels carry the vehicle’s weight and transfer torque from the axle to the road so the vehicle can move. They are not for storing energy or cooling the engine.

27. Which part directly secures the wheel to the vehicle hub?

Brake caliper
Wheel trim
Tyre valve
Wheel nuts (lug nuts)
Explanation:

Wheel nuts thread onto studs or bolts to clamp the wheel to the hub. The other parts do different jobs like controlling air or covering the wheel.

28. What does wheel alignment adjust on a vehicle?

The battery charge level
The angles of the wheels (toe, camber and caster)
The engine timing
The tyre rubber compound
Explanation:

Alignment sets the wheel angles so tyres meet the road correctly; it does not change engine or battery parameters.

29. Why is wheel balancing important?

To keep the battery charged while driving
To improve brake pad life by cooling them
To prevent vibrations by making the wheel and tyre assembly rotate evenly
To increase the tyre tread depth
Explanation:

Balancing adds small weights so the wheel/tyre assembly spins without wobble, reducing vibration and wear. It doesn't affect brakes, tread depth or battery.

30. Which condition most commonly causes uneven tyre wear on the inner or outer edge?

Low engine oil
Weak headlights
Dirty windscreen
Incorrect wheel alignment
Explanation:

If the wheels are misaligned (wrong camber or toe) the tyre edges wear faster. Engine oil, windscreen dirt or headlights do not cause tyre edge wear.

31. A bulge or bubble appears on a tyre sidewall. What should you do?

Replace the tyre immediately
Drive only on country roads to avoid damage
Inflate the tyre to higher pressure and drive carefully
Patch the inner tube and keep using it
Explanation:

A sidewall bulge means internal cord damage; the tyre can fail suddenly and must be replaced. It cannot be safely repaired or kept in use.

32. What is the common effect of driving with tyre pressure that is too low?

Increased fuel consumption and faster tyre wear
Less tyre noise at high speed
Shorter stopping distance on wet roads
Improved cornering precision
Explanation:

Low pressure increases rolling resistance and sidewall flexing, causing higher fuel use and quicker wear. It usually worsens braking and handling.

33. How often is it generally recommended to rotate tyres to even out wear?

Only when a tyre has a puncture
Once every five years no matter the distance
When the engine oil is replaced weekly
Every 8,000 to 10,000 km (or as the vehicle manufacturer advises)
Explanation:

Regular tyre rotation (about every 8,000–10,000 km) helps even wear. Waiting for punctures or doing it by time alone is not correct, and it is unrelated to weekly oil changes.

34. What is the main difference between tubeless and tube tyres?

Tube tyres are always larger in diameter
Tubeless tyres cannot be balanced
Tubeless tyres need wooden spokes
Tubeless tyres do not require an inner tube; tubed tyres do
Explanation:

Tubeless tyres form an air-tight seal with the rim and do not use inner tubes. Tubed tyres have a separate inner tube holding the air.

35. Which tool is commonly used to loosen or tighten wheel nuts when changing a tyre?

Oil filter wrench
Spark plug socket
Flat-blade screwdriver
Lug wrench (wheel spanner)
Explanation:

A lug wrench is designed to fit wheel nuts and provide the leverage needed. Screwdrivers and other tools are not suitable for wheel nuts.

36. What is the role of wheel bearings in a wheel assembly?

Measure tyre tread depth electronically
Hold the tyre valve in place
Allow the wheel to rotate smoothly while supporting vehicle load
Attach the hubcap to the wheel
Explanation:

Wheel bearings reduce friction between moving parts and carry the vehicle's load while allowing smooth wheel rotation.

37. What is the correct sequence to tighten wheel nuts after placing a wheel on the hub?

Use a star (diagonal) tightening pattern
Tighten only one nut and leave the others loose
Tighten the nearest nut fully, then the next clockwise
Tighten nuts randomly until they feel tight
Explanation:

A star pattern ensures even seating of the wheel on the hub. Tightening one nut fully first can cause misalignment and uneven clamping.

38. Why are tyre treads important for driving in wet conditions?

They store heat to warm the brakes
They reduce tyre pressure automatically
They channel water away to reduce the risk of hydroplaning
They make the tyre heavier for better stability
Explanation:

Tread grooves evacuate water from the contact patch so the tyre keeps grip on wet roads and reduces hydroplaning risk.

39. What is a characteristic of a temporary 'space-saver' spare tyre?

It is for short, low-speed use until a full-size tyre is fitted
It is filled with water instead of air
It allows normal high-speed driving for unlimited distance
It cannot be mounted on the vehicle without modification
Explanation:

Space-saver spares are smaller and rated for temporary use at low speeds and limited distance. They are not a permanent replacement.

40. How should tyre pressure be checked for the most accurate reading?

By looking at the tyre tread
Right after driving at high speed
With a tyre pressure gauge when the tyres are cold (before driving)
By pressing the tyre with your hand
Explanation:

Cold tyres give the most accurate pressure reading because heat from driving raises pressure and gives a false high reading.

41. What driving symptom usually indicates a wheel is out of balance?

Headlights dimming while driving
Vibration in the steering wheel or seat at certain speeds
Sudden loss of engine power
Doors not closing properly
Explanation:

Imbalance causes oscillating forces that produce vibration, often felt through the steering wheel or floor at certain speeds.

42. What does the term 'rim' refer to on a wheel?

The rubber tread on the tyre
The brake disc behind the wheel
The metal outer edge of the wheel that supports the tyre
The battery mounted under the seat
Explanation:

The rim is the wheel's metal part that the tyre seats against; it is not part of the tyre tread or braking system.

43. What is 'camber' in wheel geometry?

The forward or backward tilt of the steering wheel
The angle between the tyre tread grooves
The inward or outward tilt of the top of the wheel when viewed from the front
The speed rating stamped on the tyre
Explanation:

Camber is the vertical tilt of the wheel: top leaning in or out. Other answers describe different concepts.

44. Where is the safest place to position a jack when changing a wheel?

Under the bumper cover in front of the tyre
On the road surface beneath the exhaust pipe
On uneven ground under the tyre sidewall
At the vehicle's designated jacking point near the wheel on the chassis or sill
Explanation:

Designated jacking points are reinforced to safely lift the car. Using bumpers, sidewalls or unstable ground can be dangerous.

45. What can happen if wheel nuts are too loose?

The headlights will go out
The engine oil will leak
The wheel may wobble or come off while driving
The radio will stop working
Explanation:

Loose wheel nuts reduce clamping force and can allow the wheel to detach. They do not affect unrelated systems like radio or lights.

46. Which tyre condition most increases stopping distance on wet roads?

A hubcap missing
Severely worn tread
Clean windows
Shiny paint on the rim
Explanation:

Worn tread cannot channel water effectively, greatly increasing stopping distance on wet surfaces. Rim paint, hubcaps or window cleanliness do not affect tyre grip.

47. What is the primary purpose of a wheel hub?

To inflate the tyre automatically
To serve as the central mounting assembly for the wheel and house the bearings
To change gear ratios in the transmission
To display tyre pressure on the dashboard
Explanation:

The hub connects the wheel to the vehicle axle and holds the bearings. It does not inflate tyres or change gears.

48. How can you identify a directional tyre when fitting it to a vehicle?

By the tyre being larger than other tyres on the vehicle
By the colour of the tyre, which must be blue
By a metal sticker glued on the tread
By an arrow or rotation marking on the tyre sidewall showing the correct rolling direction
Explanation:

Directional tyres have arrows indicating the correct rotation direction to ensure proper water evacuation and performance.

49. What is a likely effect of over-inflating a tyre beyond the recommended pressure?

Reduced contact area with the road, harsher ride and centre tread wear
Automatic correction of wheel alignment
Improved braking in all conditions
Lower fuel consumption even if tyres are worn
Explanation:

Over-inflation makes the tyre more rounded, reducing grip and comfort and causing the centre of the tread to wear faster.

50. After lowering a vehicle from the jack, what should you do before driving away?

Paint the wheel rim to prevent rust
Spray water on the tyre to cool it down
Tighten the wheel nuts to the manufacturer's specified torque
Remove the spare tyre from the boot permanently
Explanation:

With the tyre touching the ground, final tightening to the correct torque ensures safe clamping. Other actions are irrelevant or unsafe.