Tyre size has a major impact on your 4WD’s performance, safety and reliability. 

Oversized tyres can stress suspension, alter gearing and affect braking, while undersized tyres reduce clearance and off-road capability. Checking tyre size before upgrading ensures the tyres suit your vehicle, driving style and – importantly – legal requirements.

The starting point is always the tyres’ factory specifications, which can be found on the tyre sidewall, in the owner’s manual, or on the tyre placard inside the driver’s door frame. These numbers, whether metric (265/70R16) or imperial (33×12.5R16) indicate width, sidewall height and rim diameter, helping you compare tyres and choose the right fit.

Choosing the wrong tyre size can throw off speedometer readings, affect ABS and traction control, increase fuel consumption, and cause excessive wear on suspension and driveline components. Correct sizing maintains performance, safety, and comfort.

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Superior Engineering’s Tyre Size Calculator is a free, easy-to-use tool that makes planning tyre upgrades simple. It allows you to compare your current tyres with potential upgrades, showing differences in overall diameter, width and sidewall height, while helping you ensure compliance with Australian regulations. 

While changing tyre size is a common upgrade to improve clearance and off-road grip, there are limits, and larger tyres may cause guard rubbing, altered gearing and reduced braking. Each state has legal limits on tyre increases, so planning carefully is essential.

How the calculator works

  1. Enter current tyre dimensions.
  2. Select a new tyre size.
  3. Review the comparison: See differences in diameter, width and other key metrics to visualise how your vehicle will perform.

Beyond the calculator

Upgrading to bigger tyres can affect your speedometer accuracy, but Superior Engineering offers plug-and-play speedo correctors for popular 4WD models, allowing you to recalibrate your speedo and stay compliant. 

Superior also provides suspension upgrades, GVM upgrades and engineering advice to ensure modifications are safe and legal. Using factory specs, understanding size codes and utilising the Tyre Size Calculator ensures smarter, safer tyre upgrades that balance performance, safety and comfort.

Plan your upgrade

Visit Superior Engineering’s Tyre Size Calculator today to start planning your 4WD upgrade. For personalised advice and product options, contact their sales team at (07) 5433 1411. Remember, while the calculator is a valuable planning tool, always confirm your tyre choices with a qualified tyre fitter, engineer or your vehicle manufacturer to ensure safety and compliance.