What does the ET value of a tire mean?
2 Answers
Tire ET value refers to the offset value, which is the deviation between the mounting surface of the wheel hub and the centerline of the rim, measured in millimeters. It can be positive, zero, or negative. A positive offset means the mounting surface is towards the outer side, while a negative offset means it's towards the inner side of the rim. Changing the offset of the rim will alter the wheel track of the vehicle, which is the distance between the centerlines of the tires. Therefore, simply increasing the size of the rim and tire without changing the offset will not affect the wheel track. The ET value of the tire determines whether the wheel hub will rub against vehicle components. If the new wheel hub has a larger offset than the original or is too wide, it may cause friction with the vehicle's suspension system.
To be honest, as a car enthusiast, I often discuss wheel ET values with friends. Essentially, ET stands for Einpresstiefe in German (meaning 'insertion depth'), abbreviated as Offset in English, measured in millimeters. It indicates the distance between the wheel's mounting surface and its centerline. Simply put, a positive ET value like +35mm means the mounting surface is positioned further outward, making the wheel sit slightly more inward. Conversely, a negative ET value like -20mm shifts the mounting surface inward, causing the wheel to protrude outward. This is crucial when modifying wheels because altering the ET value directly affects whether the wheel will rub against the body or brake calipers. For example, if the stock ET is +45 and you change it to +20, the wheel moves slightly outward, enhancing the car's aggressive look and improving steering precision. However, excessively increasing or decreasing the ET may cause interference with fenders, suspension components, or even the ABS system. Before swapping wheels, I always advise checking the vehicle manual for the recommended ET range—never compromise safety for aesthetics. While car mods are fun, I remind my buddies to balance functionality and style, testing adjustments step by step for the safest outcome.
