Wheel Size guide

Understanding Wheel Sizing

Thinking of changing your wheel size or style? Make sure to do your homework. Choosing wheels that don’t match your vehicle’s specifications can negatively affect handling, safety, and legality. Proper fitment is key to both performance and roadworthiness.

Wheel Sizing Explained

Wheel Diameter

Measured in inches (e.g., 16", 17", 18"). This must match or be compatible with the tyre and brake clearance. For Example: If your tyre is for a 17" rim, your wheel must also be 17".

Wheel Width

Also in inches (e.g., 7.5", 8", 9"). Affects the tyre size you can fit. Wider wheels can fit wider tyres but may require body clearance checks.

Bolt Pattern (PCD - Pitch Circle Diameter)

The number of bolts and the diameter of the bolt circle (e.g., 5x114.3). Must match your vehicle’s hub. Incorrect PCD = wheels won’t mount.

Offset (ET)

Measured in millimetres. It’s the distance from the hub mounting surface to the wheel's centerline.

  • Positive offset: wheel sits further inside the guard.
  • Negative offset: wheel sits more outward (more aggressive look)  (Incorrect offset can cause rubbing or poor handling.)

Centre Bore

The hole in the centre of the wheel that fits over the hub. Needs to match or be larger than the car’s hub bore (hub rings can help if larger)

Additional information

Maintain Overall Rolling Circumference

When changing wheel size (diameter), you must also adjust the tyre profile to keep the overall rolling circumference (wheel + tyre height) as close to the original as possible.

This ensures:

    • Accurate speedometer readings

    • Proper ABS and traction control functionality

    • Preserved fuel economy and gearing

Use a Tyre Size Calculator

A tyre size calculator can help you find suitable tyre dimensions when upsizing or downsizing wheels. For Example: Going from 16" to 18" wheels may require a lower-profile tyre to keep the overall diameter the same.

Watch for Guard and Suspension Clearance

Bigger or wider wheels can rub against the fenders, inner guards, or suspension components if not properly offset. Always check fitment or test-fit wheels before purchasing.

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