Wheel Offset Calculator

What is a wheel offset? Modifying your ride with aftermarket wheels and tyres is a fun way to make your car or 4x4 a king of the streets.

Proper offset ensures your new package has enough clearance so nothing rubs against the suspension, brakes or vehicle body (like fenders, bumpers and mud flaps). Which is why it helps to understand a little bit about offsets.

Wheel Offset and Backspacing Explained

Offset refers to how your car or 4x4's wheels are positioned within the guards of your vehicle. It is measured in mm from the centreline of the wheel and terms such as ‘et 45' or ‘+45' or ‘pos 45' are used. Read below for further explanation:

• Positive wheel offset

  Is when the hub mounting surface is in front (more toward the street side) of the centreline of the wheel. (see image below) Most modern vehicles have a factory positive offset, as manufacturers are making more use of space in the engine body, making guards smaller and more aerodynamic.

• Zero-wheel offset

  Is when the hub mounting surface of the wheel is in line with the centreline of the wheel. (See image below) Using a lower offset wheel will push the whole wheel further away from the car and may be done for a few reasons.

  1. Aesthetics- Filling out the guards of a sedan or 4x4 dosent always need to be done with bigger tyres, sometimes just adjusting to offset is all that's needed.
  2. Brake clearance. Factory wheels often leave only the minimum required clearance for standard brakes. This can become an issue when upgrading to larger brake packages. Lower offset wheels often provide more clearance for these types of upgrades.

• Negative offset

  Is when the hub mounting surface is behind the wheel centreline. See below. Negative offset wheels will generally give you deep dish or deep lip as most of the wheel width is on the outside of the spoke. Low to negative offset wheels tend to only fit early model cars because of their tendency to have smaller brakes, and larger guard clearance. Some 4x4 can fit negative offset wheels, usually when extended flares have been attached to prevent excessive ‘poke' of the rim and tyre.

Easily calculate your offset and changes to offset with this online calculator: Wheel Offset Calculator.

If you have any further questions relating to wheel offsets, simply contact our highly qualified staff on 02 8880 4628.