ET drive failure: what is it and why it cannot be ignored

Disc offset is one of those parameters that many car owners learn about only after purchasing new wheels. Meanwhile, wrong ET (from German EinpressTiefe) can turn your ride into a nightmare, from vibrations in the steering wheel to premature wear of the suspension. Why do manufacturers regulate this indicator so strictly? And what happens if you install wheels with an offset different from the factory one?

In this article we will look at how offset affects wheel geometry, why changing it is akin to interfering with the car’s design, and whether it is possible to “deceive” the system using spacers. You will also learn how to measure ET yourself and what mistakes are most often made when selecting discs.

Spoiler: even a minimal deviation of 5–10 mm can lead to wheel bearing will fail twice as fast. And if the offset differs by 20 mm or more, get ready for problems with the steering and brakes.

What is disc offset ET and how is it measured?

Disc offset (indicated as ET or offset) is the distance between the mating plane of the disk (the one that is pressed against the hub) and the imaginary central axis of the disk. It is measured in millimeters and can be:

• 🔹 Positive (ET40, ET35) - the mating plane is shifted to the outer side of the disk. Such discs are “recessed” inside the arch.
• 🔹 Zero (ET0) - the plane coincides with the central axis.
• 🔹 Negative (ET-10, ET-20) - the plane is shifted inward, the disk “sticks out” outward.

For example, the inscription ET45 on the disk means that the mating plane is 45 mm away from the center towards the outer edge. The larger the number, the deeper the disk “sits” in the arch.

Important: departure do not confuse with disk width (for example, 7.5J) or diameter (R17). These are independent parameters. Same disk 8Jx18 may have an overhang ET30 or ET50 - and this will completely change his behavior in the car.

Why do manufacturers strictly regulate departure?

Disc offset is not a whim of engineers, but the result of complex calculations of suspension loads. By changing ET, you are actually moving the wheel's fulcrum, which results in:

⚠️ Attention: If the offset differs from the factory one by more than ±5 mm, this is considered a change in the vehicle design. In some countries (for example, Germany) this requires mandatory certification.

Let's figure out what happens when you deviate from the recommended departure:

ET deviation	Consequences for the car
ET increased (for example, instead of ET45 set ET55)	The wheel is “recessed” into the arch, reducing the track. The load on wheel bearings and shock absorbers. The steering wheel becomes “heavy”.
ET reduced (for example, instead of ET45 set ET30)	The wheel sticks out, the track expands. The load on suspension arms and steering rods. It is possible to hit the arch when turning.
ET=0 or negative (for example, ET-10)	The wheel is very offset outward. Risk of damage brake hoses and ABS sensors. Exchange rate stability deteriorates at high speeds.

A critical deviation of the offset by 15-20 mm from the factory one can lead to the suspension geometry going beyond the tolerances established by the manufacturer. This is fraught not only with accelerated wear of parts, but also with loss of control over the car in an emergency.

How offset affects handling and safety

Many car owners mistakenly believe that offset is a “trifle” that can be ignored if the disk physically fits onto the hub. However, even a small change in ET dramatically changes the distribution of forces in the suspension. Let's take a closer look:

• 🚗 Steering: With a reduced reach (the disc “sticks out”), the steering wheel becomes sharper, but loses “feedback”. When enlarged (the disk is “recessed”), more effort is required to turn.
• 🔄 Directional stability: Incorrect ET bias roll center (roll center), which causes the car to “yaw” along the road, especially on uneven surfaces.
• 🛑 Braking distance: Changing the load on the wheel bearings can cause them to play, which increases the braking distance by 10–15%.
• 🔥 Tire wear: Uneven weight distribution accelerates tread wear. For example, when ET+10 Normally, the inner edge of the tire wears out 2 times faster.

It is especially dangerous to change the reach on vehicles with multi-link suspension (for example, Volkswagen Golf, BMW 3-series). Here, even a minimal shift of the wheel leads to the levers starting to work at incorrect angles, which leads to their deformation.

How to measure disc offset yourself

If you bought discs secondhand or are in doubt about the markings, you can measure the offset yourself. You will need:

• 📏 Ruler or caliper (preferably with a depth gauge).
• 📐 Square or even strip.
• 🧲 Magnet (to search for the mating plane).

Measurement algorithm:

1. Place the disc on a flat surface face down.
2. Place the rack against the rim of the disc (it should touch the edges).
3. Measure the distance from the mating plane to the bottom edge of the rail (distance A).
4. Turn the disk over and measure the distance from the mating plane to the top edge of the rack (distance B).
5. Departure ET = (B – A) / 2.

Example: if A = 100 mm, and B = 140 mm, then ET = (140 – 100) / 2 = 20 mm.

Can spacers be used to adjust offset?

Wheel spacers are metal rings that are installed between the hub and the disk, artificially changing the offset. They are:

• 🔧 Universal - Suitable for most vehicles, but require extended bolts.
• 🔧 Individual — are manufactured for a specific model, taking into account DIA (diameter of the central hole).

At first glance, spacers seem like a simple solution: if you want to change the offset, install a ring of the required thickness. However, there are pitfalls here:

⚠️ Attention: Spacers with a thickness of more than 10 mm require the use of bolts with an enlarged threaded part. If you ignore this rule, the bolts may not withstand the load and break.

When spacers you can use:

• ✅ To adjust the offset within ±5 mm (for example, with ET45 on ET40).
• ✅ When installing wider rims, if the factory ET does not allow you to avoid friction on the arch.

When spacers it's impossible use:

• ❌ If the offset differs from the factory one by more than 10 mm.
• ❌ On cars with aluminum suspension arms (for example, Audi A4 B8, Mercedes C-Class W205).
• ❌ If the spacer does not have a centering collar (risk of wheel beating).

What happens if you put a 20mm spacer on a rim with ET45?

Such a wheel will actually have an offset of ET25, which on most cars will result in the wheel moving outward by 20mm. Consequences:

- The load on the wheel bearing will increase by 1.5–2 times.

- Steering rods will work at the wrong angle, which will accelerate the wear of the silent blocks.

- It is possible for the tire to touch the arch or suspension elements when the vehicle is fully loaded.

Typical mistakes when selecting wheels by offset

Even experienced car owners sometimes make mistakes when choosing wheels. Here are the most common mistakes:

1. Trust in “universal” tables. On the Internet you can find disk “compatibility” tables, which indicate that Toyota Corolla ET from 35 to 45 is suitable. However, the manufacturer clearly prescribes ET45 - and this is not without reason. A deviation of even 5 mm can lead to vibrations.
2. Ignoring disk width. Wide disk (eg. 9J instead of 7J) automatically requires a smaller offset, otherwise the wheel will catch on the arch. But many people forget about this rule.
3. Buying discs based on appearance. Discs with a negative offset (ET-10, ET-20) look aggressive, but on most sedans and hatchbacks they are unacceptable due to overloading the suspension.
4. Failure to take into account vehicle modifications. For example, at Volkswagen Passat B6 The offset of the front and rear discs is different: ET45 front and ET40 behind. By mixing them up, you will get uneven tire wear.

Another common mistake is to believe sellers who say: “It’s only 5 mm, no big deal.” In fact, even such a deviation can lead to ABS will begin to operate ahead of time due to a change in the position of the sensor relative to the rotor tooth.

What disc offset is suitable for popular car models?

To make it easier for you to navigate, we have collected data on factory offsets for popular models. Please note: even within the same model, the offset may vary depending on the year of manufacture and body type.

Car model	Year of manufacture	Factory offset (ET), mm	Notes
Toyota Corolla (E210)	2019–2026	45 (front), 45 (rear)	For versions with discs R16 and R17.
Volkswagen Golf (Mk7)	2013–2020	48 (front), 45 (rear)	For disks 7Jx16. On versions with R18 maybe ET45.
Hyundai Solaris (HC)	2017–2026	46 (all wheels)	For basic configurations. In sports versions there may be ET40.
Kia Rio (YB)	2017–2023	48 (front), 49 (rear)	A difference of 1 mm between the axles is the norm for this model.
Lada Vesta	2015–2026	40 (front), 42 (rear)	For disks 6Jx15 and 6.5Jx16.

Before purchasing discs, always check with badge on the center pillar (from the driver's door) or with data in PTS. If there is no information, use online catalogs of disk manufacturers, for example, BBS, OZ Racing or Kosei.

FAQ: Frequently asked questions about disc ejection

Is it possible to install wheels with an offset of ET35 instead of ET45?

Theoretically it is possible, but this will lead to the wheel moving outward by 10 mm. On most cars this will cause:

• Increased load on the wheel bearing.
• Risk of the tire hitting the arch when fully loaded or on uneven surfaces.
• Changing the wheel alignment angles (the wheel alignment will have to be done again).

If you want just such a visual effect, it is better to use 10 mm thick spacers on wheels with ET45.

How does offset affect wheel alignment?

Changing the offset moves the wheel horizontally, which automatically changes roll-in shoulder (distance between the point of contact of the tire with the road and the steering axis of the wheel). This leads to:

• Need for reconfiguration toe-in (wheel rotation angles).
• Possible change camber (angle of inclination of the wheel in the vertical plane).

After installing wheels with another ET, be sure to visit the wheel alignment stand.

What is more dangerous: increased or decreased overhang?

Both options are harmful, but reduced overhang (the disk “sticks out”) considered more dangerous because:

• The leverage of force acting on the wheel bearing increases, which accelerates its wear.
• There is an increased risk of damage to the brake hose or ABS sensor when hitting an obstacle.
• Exchange rate stability deteriorates at high speeds.

An increased offset (the disc is “recessed”) has less impact on safety, but can lead to friction between the tire and the suspension elements.

Is it possible to drive with different offsets on the front and rear axles?

No, this is absolutely not recommended. Different offsets on the axles lead to:

• Uneven distribution of braking forces (the car may pull to the side when braking).
• Changes in the behavior of the car when cornering (the front and rear axles “behave” differently).
• Accelerated wear of the differential (in all-wheel drive vehicles).

An exception is some sports cars, where different offsets are built into the design (for example, Nissan GT-R), but this is confirmed by factory documentation.

What disc offset is best for tuning?

For tuning, wheels with negative or zero offset (for example, ET0 or ET-10) so that the wheel “sticks out” as much as possible. However this requires:

• Settings stretched bolts or extended studs.
• Uses spacers with centering collar.
• Checks for the absence of contact of the tire with the arch or suspension elements.

Remember: such tuning negatively affects suspension life and may be prohibited by traffic regulations (in some countries, the overhang is considered part of the car's design).