Departure on the wheel (ET): what it is, how to measure and why a 5mm error can ruin the suspension

Introduction: why the disk is not a “trifle”, but a critical parameter

Have you ever wondered why the same discs fit perfectly on the same disk? Volkswagen Golfbut are not necessarily suitable for Skoda OctaviaBut are they identical in diameter and width? The reason lies in the mysterious letters. ET - the designation of the departure of the disc, which many car owners ignore until they encounter a problem: knocking in the suspension, uneven wear of tires or even refusal to pass the inspection.

The drive's departure (or take-off) is the distance between the wheel's landing plane (the one pressed against the hub) and the imaginary central axis of the disk. It is measured in millimeters and can be positive, zero or negative. It would seem that this is difficult? But An error of only 5-10 mm can cause the wheel to shift relative to the hub, which will increase the load on bearings, shock absorbers and steering racks by 20-30%.. This is no longer a matter of comfort, but a matter of safety.

In this article, we will discuss:

• 🔧 What is it? ET How to decipher it on the labeling of the disk
• 📏 How to measure your flight (even without special tools)
• ⚠️ Consequences of improper departure: from vibration on the steering wheel to suspension breakdown
• 🔄 Can I put disks with another ET and how to compensate for it?
• 📑 Where to find the right settings for your car

What is a Disk Departure (ET) and How to Read It on Labeling

Each wheel drive has a marking that looks something like this: 7.5Jx16 ET45 5x112 PCD 66.6. Here. ET45 - This is the departure where:

• ET (from German) EinpressTiefe) - departure designation;
• 45 - value in millimeters.

There are three types of flights:

• 🔹 Positive (ET > 0) - the landing plane is displaced outward relative to the center of the disk. Most often found on front-wheel drive cars (for example, ET35–ET45 for Toyota Corolla).
• 🔹 Zero (ET = 0) - the landing plane coincides with the central axis. Typical for SUVs and some sports models.
• 🔹 Negative (ET < 0) - the landing plane is drowned inside. It is used to expand the track (for example, ET-10 on Nissan Patrol).

It is important to understand that the flight is disk-width It's not its diameter. For example, a disk. 8Jx17 ET30 and 8Jx17 ET40 They will be equally wide, but in different ways “sit” on the hub. The first will push the wheel outwards 10 mm more than the second.

How to measure the drive departure yourself: step-by-step instructions

If the marking on the disk is erased or you buy used wheels without documents, the departure can be measured manually. You'll need:

• 📏 Line or bar (better with a depthmeter);
• 📐 A corner or a flat rake;
• 🖍️ Marker or pencil.

Step 1. Find the landing plane This is the surface of the disc that is pressed against the hub. It is usually smooth and processed more carefully than the rest of the parts.

Step 2. Measure the width of the disc (A) The distance between the inner edges of the rim (not on the outer sides!). For example, if the disc is marked as 7.5JIts width is 7.5 inches (190.5 mm).

Step 3. Measure the distance from the landfill plane to the inner edge (B):

• Apply the rack to the rim so that it lies on the inner edge.
• Measure the distance from the landfill to the rake.

Step 4. Calculate the flight by the formula:

ET = (A / 2) – B

Where:

• A - disc width in mm;
• B The distance from the landing plane to the inner edge.

Prepare a flat area |Clean the disk of dirt |Find the landfill plane |Measure the width of the disk (A)|Measure the distance to the inner edge (B)| Calculate ET by the formula-->

Example: if the width of the disc (A) is 200 mm and the distance (B) is 120 mm, then: ET = (200/2) - 120 = 100 - 120 = -20 mm (negative relegation).

⚠️ Attention: If the disk has a complex geometry (for example, with deep pockets under the spokes), it is better to measure the departure on a removed wheel or in a tire fitting. A 2-3mm error can be critical for some car models.

Consequences of improper departure: from vibration to suspension breakdown

Many car owners believe that if the disc physically “stands” on the hub, then it can be used. That's a dangerous misconception. Even a small deviation from the standard value leads to:

Deviation ET (mm)	Effects of consequences	Risk to the car
±2-5 mm	Increased wear of the hub bearings, slight vibration on the steering wheel	Low (but reduces the resource of details)
± 6-10 mm	Steering axle displacement, uneven tyre wear, suspension knock	Medium (requires correction of collapse-convergence)
±11-15 mm	Severe vibration, car sideways, damage to shock absorbers	High (possible emergency situations)
>15 mm	Contact of the wheel with the arch or suspension details, loss of controllability	Critical (exploitation prohibited)

Especially dangerous. negative departure on front-wheel drive vehicles. For example, if Hyundai Solaris factory-wise ET46 disk off ET30The wheel will move outwards by 16 mm. It'll lead to:

• 🔧 Increased load on the hub bearing (the resource is reduced by 2-3 times);
• 🚗 Change of the shoulder run-in, which will make the steering wheel "heavy" and unpredictable;
• 💥 Risk of hitting the wheel behind the arch when fully turning or loading.

In rear-wheel drive vehicles (e.g., BMW 5 Series) the effects may be less noticeable but will still lead to accelerated wear on the Silentblocks and suspension bushings.

Can I put discs with a different departure and how to compensate for it?

Theoretically, yes, but with reservations. Manufacturers may allow slight deviations (usually ± 5 mm), but only if:

• 🔹 The drive is certified for your car model.
• 🔹 The width and diameter correspond to the factory parameters;
• 🔹 After installation, there is no contact of the wheel with the suspension elements or body.

If the difference is greater, there are two ways to compensate:

1. Use of paddles Metal rings that increase the flight. For example, if you need to. ET35And the disk. ET20You can put a box thickness of 15 mm. But this:
• ⚠️ Increases the load on the bearings;
• ⚠️ Can cause the wheel to beat with poor quality of the draw;
• ⚠️ Prohibited by some traffic rules (in Russia, the expanses are not certified for road use).

Selection of disks with a different ET, but with width adjustment. For example, if you reduce the width of the disk by 10 mm, you can compensate for the increase in departure by 5 mm (but this requires accurate calculations!).

⚠️ Attention: On all-wheel drive vehicles (Audi Quattro, Subaru Symmetrical AWD) a change in departure even by 5 mm may disturb the balance of the transmission and cause accelerated wear of the differentials. The tolerances are stricter here - usually ± 2 mm.

If you are in doubt, it is better to use it. departure calculator (There are sites like this one) Wheel-Size.com) or consult a 3D scanner in the tire fitting to check the wheel landing.

What happens if you put the ET discs 20 mm smaller than the factory?

The wheel will move outwards, which will lead to:

Contact of the tire with the arch when cornering or loading (for example, with a full trunk);

Increased shoulder run-in, which will make the steering wheel “lighter”, but less informative;

Risk of "breaking out" of the steering wheel when falling into the hole at speed;

Accelerated wear of hub bearings (3-5 times faster).

On some vehicles (e.g., Mercedes-Benz system 4MATIC) this may lead to errors in the ESP and ABS.

Where to Find the Right Departure for Your Car

The most reliable source. manual or a sticker on the door (where the recommended sizes of tires and discs are indicated). If there is no documentation, check:

• 🔧 Official website of the manufacturer (Section "Technical characteristics"). For example, for Ford Focus 3 factory ET -- 50-52 mm depending on the engine.
• 📄 Disc directories (e.g., Alloy Wheels Direct, Replica Wheels). Specify the exact model, year and modification of the car.
• 🔍 Ownership forums (e.g., Drive2 or Club-Toyota). Successful examples of non-standard discs are often discussed.

Pay attention to this. extravariancewhich affect compatibility:

• PCD (blathering) - for example, 5x112 for Volkswagen;
• DIA (diameter of the central hole) - must match or be more factory (transition rings are used);
• J - shape of the rim edge (affects the landing of a tubeless tire).

Example Renault Duster 2020:

• Factory departure: ET50;
• Permissible range: ET45–ET55 according to the data Renault);
• Blur: 5x114.3;
• DIA: 66.1 mm.

Frequent errors in the selection of disks on departure

Experienced tire repair professionals say that customers often make the following mistakes:

1. Ignoring the year of the model release. For example, Kia Rio 2015 and Kia Rio 2020 They may have different departures due to suspension upgrades.
2. Buying discs "in appearance", without checking ET. The disc may look perfect, but have a relegation ET20 instead ET40.
3. Trusting vendorsThose who say “everything will work.” This is especially common when buying replicas or used discs.
4. Not taking into account the width of the disk.. For example, if you put on Lada Vesta wide 8J instead 6.5JEven with the right ET, the wheel can catch the arch.

Another common problem is that Buying Universal Discs (e.g., 5x114.3 for Toyota and Nissan). It would seem that the PCD is the same, but the flight may be different. For example:

• Toyota Camry — ET45;
• Nissan Teana — ET35.

10 mm difference and the disc from Teana not suitable CamryBut, “by eye” they are the same.

FAQ: Answers to Frequent Questions About Disk Departure

Can I put the drives with a departure ET0 on the front-wheel drive car, if the factory ET45?

No, it's critically dangerous. Shifting the wheel outwards by 45 mm will result in:

• Strong load on hub bearings (the resource will be reduced by 5-10 times);
• Contact of the tire with the arch or suspension details when cornering;
• Unpredictable behavior of the car at speed (especially during emergency braking).

The only option is to use 45 mm thick stretchers, but this is an uncertified solution and may be prohibited by traffic rules.

Which flight is better for tuning: positive or negative?

It depends on the goal:

• 🔹 Negative ET (e.g., ET-10) widens the track, improves cornering stability and gives an aggressive appearance. But increases the load on the suspension and may require the completion of the arches.
• 🔹 Positive ET (e.g., ET50) narrows the track by reducing the load on the hubs, but impairs handling at high speeds.

For urban tuning is optimal ET20–ET30 (with the scoring if necessary). Drag or drift is often used for ET0–ET-15But that requires a stronger suspension.

Does the flight affect fuel consumption?

Yes, but indirectly. The shift of the wheel outwards (reducing ET) increases the shoulder The distance between the point of contact of the tyre with the road and the axis of rotation. This leads to:

• Increased steering effort (especially at low speeds)
• Increased rolling resistance, which can increase fuel consumption by 1–3%;
• More intense wear of tires due to uneven distribution of load.

However, the effect is noticeable only with significant deviations (more than 10 mm from the factory ET).

Can I use the disk to change the flight?

Technically, yes, but it is. highly recommended. When flowing:

• Disk balance is disturbed;
• Decreased strength (especially if the disk is cast or forged);
• The paintwork may be damaged, which will lead to corrosion.

It is better to buy a drive with the desired ET or use certified spacers (if allowed by the car manufacturer).

How to check if the drive is suitable for departure without installing it on the car?

There are three ways:

1. Compare it to a factory disc.Apply the new disc to the old landing plane upwards and check how displaced the central axis.
2. Use a 3D model: on sites like Wheel-Size.com You can virtually “try on” the drive on your model of car.
3. Consultation in the tire fitting with a 3D scanner (e.g., Hunter GSP9700), which will show possible gratuities and displacements.