DFFT Tires and Wheels 2 — Questions and Answers
Question 1: A vehicle exhibits excessive body lean during cornering and the tires show wear on the outer shoulders. Which fault best explains both symptoms?
- Weak or worn front anti-roll bar (sway bar) (Correct answer)
- Overinflated tires
- Incorrect wheel offset
- Rear wheel misalignment
Correct answer: Weak or worn front anti-roll bar (sway bar)
A worn anti-roll bar allows excessive body roll during cornering, loading the outer tires heavily and causing outer shoulder wear while also making the vehicle lean noticeably.
Question 2: When inspecting a set of tires, you notice that both rear tires show wear only on the inner edges. What alignment fault does this suggest?
- Excessive negative camber at the rear (Correct answer)
- Excessive positive camber at the rear
- Rear toe-in beyond specification
- Rear toe-out beyond specification
Correct answer: Excessive negative camber at the rear
Excessive negative camber tilts the top of the wheel inward, placing more load on the inner edge of the tire and causing inner edge wear.
Question 3: A tire pressure monitoring system (TPMS) warning light illuminates while driving. What is the correct first action?
- Stop safely and check all tire pressures with a calibrated gauge (Correct answer)
- Continue driving carefully to the nearest service station
- Increase tire pressure to the maximum door placard value
- Reset the TPMS by disconnecting the vehicle battery
Correct answer: Stop safely and check all tire pressures with a calibrated gauge
The TPMS warning indicates a tire is at least 25% below the recommended pressure; the correct response is to stop safely and verify pressure with a gauge before continuing.
Question 4: What fault would most likely cause a rhythmic thumping noise that increases in frequency with vehicle speed and is felt through the floor at all speeds?
- A flat spot on the tire from wheel lockup (Correct answer)
- A cracked wheel rim
- Mismatched tire sizes front to rear
- Excessive caster angle
Correct answer: A flat spot on the tire from wheel lockup
Flat spots develop on tires after prolonged wheel lockup during emergency braking and create a rhythmic thump that matches tire rotation frequency.
Question 5: During a pre-drive inspection, a driver notices that one front tire appears lower than the others. Which of the following faults would cause a slow air leak from a tubeless tire?
- A nail embedded in the tread
- A crack in the wheel rim bead seat
- Valve stem deterioration
- All of the above (Correct answer)
Correct answer: All of the above
All three — a puncture from road debris, a cracked bead seat, and a degraded valve stem — are common causes of slow air loss from tubeless tires.
Question 6: A technician rotates tires front to rear and notices that the rear tires are worn significantly more than the fronts on a front-wheel-drive vehicle. What does this suggest?
- The tires were not rotated at the recommended intervals (Correct answer)
- The rear brakes are dragging excessively
- The rear suspension camber is misaligned
- The vehicle has an active all-wheel-drive system fault
Correct answer: The tires were not rotated at the recommended intervals
On a front-wheel-drive vehicle, the front tires wear faster due to combined steering, braking, and driving loads; if the rears are more worn, tire rotation was neglected.
Question 7: What is the most accurate way to determine whether a tire should be replaced due to age, even if tread depth is still acceptable?
- Check the tire's DOT date code for manufacture date older than 6–10 years (Correct answer)
- Measure the hardness of the tread compound with a durometer
- Inspect for any visible sidewall cracking
- Compare the tire's color to a new tire of the same brand
Correct answer: Check the tire's DOT date code for manufacture date older than 6–10 years
The DOT date code (last four digits indicating week and year) allows technicians to assess tire age; most manufacturers recommend replacement after 6–10 years regardless of tread depth due to rubber degradation.
