What does “ET” stand for on rims, and how does it affect the car?

What does “ET” stand for on rims, and how does it affect the car?

The abbreviation “ET” stands for “offset” and refers to the distance between the rim’s center and the rim’s contact surface. The offset value is expressed in millimeters (mm) and can have both positive and negative values.

Knowing that the slant of a wheel has a significant impact on vehicle performance in numerous ways is crucial. Here are some significant considerations to be taken into account:

  • Track width: The ET is the distance between the two wheels on an axle. The larger the ET, the closer the rim gets to the wheel arch, and the vehicle’s track width narrows. A wider track width can improve driving stability, while a narrower track width can lead to more agile handling.
  • Wheel cover: The ET also impacts the wheel cover, which is the distance between the rim and the wheel case. A bigger tire usually covers more of the wheel, while a smaller tire size can make the rim stand out more. Wheel coverage is essential for keeping spray, dirt, and other contaminants from getting on the vehicle.
  • Brake clearance: The ET can also impact the support of the brake system. If the ET is too low, the rim might hit the brake parts and cause damage. Therefore, it is indispensable to make sure that the ET you choose has enough room for the brake system.

It should not be forgotten that ET can vary from vehicle to vehicle. Manufacturers specify the allowable ET values for each vehicle model to ensure optimum vehicle performance and safety. 

How does the “ET” affect vehicle performance?

Some effects of offsetting on vehicle performance are as follows:

  • A rim with a diameter of +40 mm has a broader track than a rim with a diameter of +25 mm. This leads to enhanced driving stability at elevated speeds.
  • It is better to have an ET of +40 mm than an ET of +25 mm because it prevents splash water, dirt, and other contaminants from entering the wheel housing.
  • A rim with an ET of +40 mm has less brake clearance than one with an ET of +25 mm. This could result in damage to the brake components.


The ET specifications of the vehicle manufacturer are important when selecting rims.

An incorrect offset can have serious consequences for vehicle performance and safety.