DFFT Tires and Wheels

Question 1

A driver reports that the vehicle pulls to the left during braking. Which tire-related fault is most likely responsible?

Accepted Answer

Uneven tire pressure between the front tires

Answer

Uneven tire pressure between the front tires causes one side to have more contact patch than the other, creating a pulling force during braking.

Question 2

What does a feathered or sawtooth wear pattern across the tread blocks of a tire typically indicate?

Accepted Answer

Toe misalignment

Answer

Feathered or sawtooth tread wear is a classic sign of toe misalignment, where the tires are angled inward (toe-in) or outward (toe-out) excessively.

Question 3

A technician finds cupping (scalloped) wear around the circumference of a rear tire. What is the most probable cause?

Accepted Answer

Worn or damaged shock absorbers

Answer

Cupping or scalloped wear is caused by worn shock absorbers that allow the tire to bounce and lose contact with the road, producing uneven wear patches.

Question 4

Which symptom would most likely indicate that a tire is significantly underinflated?

Accepted Answer

Wear concentrated on both outer edges of the tread

Answer

Underinflated tires flex excessively, causing the outer edges of the tread to bear more load than the center, producing wear on both shoulders.

Question 5

A driver complains of severe vibration felt through the steering wheel at highway speeds. The vibration disappears at low speeds. What is the most likely tire or wheel fault?

Accepted Answer

Wheel imbalance

Answer

Wheel imbalance causes a speed-dependent vibration that increases with vehicle speed because the out-of-balance mass creates a centrifugal force proportional to the square of rotational speed.

DFFT - Driver Fault Finding Test Practice Test

DFFT - Driver Fault Finding Test Practice Test

DFFT Tires and Wheels