The ET value of a wheel (short for the German term Einpresstiefe) is the distance, expressed in millimeters, between the center of the wheel and the mounting surface that secures the wheel to the hub. The ET value can be positive, zero, or negative. This value is part of the wheel’s official specifications and is always given in millimeters
Why is the ET value important?
The ET value determines how the wheel is positioned on the hub and how forces are transmitted while driving. This directly affects the load on the wheel bearing, the clearance around the brakes and suspension, and the vehicle’s track width. If the wheel is positioned too far inward or outward, it places additional stress on the bearing and the wheel suspension. Especially for trucks, a correct ET value is important to prevent unnecessary wear and problems.
Reading the ET Value
The ET value is usually easy to find on the rim itself. It is often stamped or cast on the inside of the rim and is part of the complete rim size. When replacing or swapping rims, it’s always wise to check this value.
Deviating ET Value
Deviating from the specified ET value can affect the vehicle’s safety. This can include reduced driving stability and steering precision, especially when heavily loaded or traveling at high speeds, as well as uneven and accelerated tire wear with an increased risk of overheating or blowouts. It also places additional stress on wheel bearings, axles, and wheel bolts, which can lead to mechanical failures.
For truck tires, deviations from the recommended specifications are therefore usually permitted only to a very limited extent and require expert advice.
Frequently Asked Questions
What is the ET value of a rim?
The ET value is the distance in millimeters between the center of the rim and the mounting surface that secures the rim to the hub. It is a measurement that indicates how deep the rim sits within the wheel well.
Where can I find the ET value of my rim?
The ET value is usually marked on the rim itself, on the inside, as part of the rim designation. For example, ET45
How do I calculate the ET value?
In practice, you don’t calculate the ET value yourself; instead, you read it off the rim or look it up in the manufacturer’s specifications.
How much can you deviate from the ET value?
For trucks, deviations are usually not allowed or only permitted to a very limited extent. Not sure? Then it’s wise to seek advice from a specialist.
