“ET on wheels” refers to the wheel’s offset , a key measurement that tells you how far the wheel’s mounting surface sits from the wheel’s centerline and how deep the wheel sits in the arch.

What is ET on wheels?

  • ET is an abbreviation of the German word “Einpresstiefe,” meaning insertion depth or offset.
  • It is measured in millimetres and stamped on the wheel, for example “ET35” or “ET45.”
  • ET tells you whether the wheel sits more inward (toward the suspension) or outward (toward the fender) on the car.

How ET is defined

  • Picture a cross‑section of a wheel: draw a line through the middle (the centreline) and note where the hub mounting face is.
  • The distance between that mounting face and the centreline is the ET value.
  • ET0 means the mounting face is exactly on the wheel’s centreline.

Positive, negative and zero ET

  • Positive ET (e.g., ET45) : The mounting face is closer to the outside face of the wheel, so the wheel sits further inside the arch.
  • Negative ET (e.g., ET‑12) : The mounting face is closer to the inside edge, so the wheel sticks further outwards.
  • Zero ET (ET0) : The mounting face is exactly in the middle; the wheel is equally “in” and “out.”

Why ET (offset) matters

  • Steering and handling: Changing ET alters track width and leverage on suspension parts, which can change steering feel and stability.
  • Clearance: Too low ET can make wheels rub the fender; too high ET can cause contact with brakes, struts, or inner arch.
  • Wear and safety: Incorrect offset can increase bearing and suspension wear and may make the car unsafe or illegal if wheels protrude past the body.

Simple example

  • If your original wheel is ET35 and you fit an ET25 wheel of the same width, the new wheel will stick out about 10 mm more than stock.
  • That small numerical change can be enough to cause rubbing or to change how the car tracks over bumps.

Practical tips if you’re choosing wheels

  • Always check the manufacturer’s recommended ET range for your specific car model.
  • When changing width, use an offset calculator and keep the new ET as close as possible to OEM to avoid clearance issues.
  • Look for the ET stamp on the back of the wheel spokes or mounting face when comparing or buying wheels.

Bottom note: Information gathered from public forums or data available on the internet and portrayed here.

If you tell me your current wheel size and ET plus the car model, I can outline what ET range is usually safe and how much “poke” or tuck you can expect.