Car Tuning Car Tuning Wheel and Tire Upgrades 1 — Questions and Answers
Question 1: What does the term 'plus sizing' refer to when upgrading wheels?
- Increasing wheel diameter while keeping overall tire diameter the same (Correct answer)
- Increasing both wheel diameter and overall tire diameter
- Increasing tire width only
- Increasing wheel offset only
Correct answer: Increasing wheel diameter while keeping overall tire diameter the same
Plus sizing means fitting a larger diameter wheel with a lower-profile tire so the overall rolling diameter stays nearly identical to the stock setup.
Question 2: What does 'ET' or 'offset' indicate on a wheel specification?
- The distance in millimeters from the wheel's centerline to its mounting face (Correct answer)
- The diameter of the wheel in inches
- The weight rating of the wheel in pounds
- The bolt pattern spacing in millimeters
Correct answer: The distance in millimeters from the wheel's centerline to its mounting face
Offset (ET) is the distance in mm from the wheel's hub mounting surface to its true centerline, affecting how far the wheel sits inboard or outboard.
Question 3: Which tire aspect ratio would give the shortest sidewall height on a 255mm wide tire?
- 255/30 (Correct answer)
- 255/40
- 255/50
- 255/65
Correct answer: 255/30
A lower aspect ratio number means the sidewall height is a smaller percentage of the tread width, so 30-series gives the shortest sidewall.
Question 4: What is the primary risk of running a wheel with excessive positive offset on a front-wheel-drive car?
- Increased stress on wheel bearings and inner fender rubbing (Correct answer)
- Reduced brake rotor clearance
- Decreased tire traction
- Loss of power steering assist
Correct answer: Increased stress on wheel bearings and inner fender rubbing
Excessive positive offset pushes the wheel inward, stressing bearings with extra leverage and risking contact between the tire and inner fender or suspension components.
Question 5: What is the purpose of hub-centric wheel rings (hub rings)?
- To fill the gap between the wheel center bore and the vehicle hub for vibration-free fitment (Correct answer)
- To increase the wheel's load rating
- To prevent wheel studs from loosening
- To adapt a 5-lug wheel to a 4-lug hub
Correct answer: To fill the gap between the wheel center bore and the vehicle hub for vibration-free fitment
Hub rings center the wheel precisely on the hub, eliminating vibration caused by a loose fit between aftermarket wheel bores and smaller factory hubs.
Question 6: What is the recommended practice after installing aftermarket wheels regarding lug nut torque?
- Re-torque the lug nuts after the first 25–50 miles of driving (Correct answer)
- Only torque them once at installation
- Use threadlocker on the studs
- Torque them 20% above the factory spec
Correct answer: Re-torque the lug nuts after the first 25–50 miles of driving
After initial driving, wheels and mating surfaces 'seat' together, so re-torquing ensures lug nuts remain at the correct clamping force.
Car Tuning Car Tuning Wheel and Tire Upgrades 1
What does the term 'plus sizing' refer to when upgrading wheels?