Rim offset: definition, location and size
Content
The choice of rim size mainly depends on the size of the tire fitted to your vehicle. The offset is related to the width of the rim. It is also called ET, from the German Einpress Tiefe, or Offset in English. Measuring the rim offset will also determine the position of the wheel in relation to its passage.
🚗 What does rim offset mean?
Un offset from Rim is the distance between your vehicle's wheel hub mounting point and the symmetry surface of its rim. Expressed in millimeters, it allows you to partially know the position of the wheel and the appearance of the disks on it.
For example, a large rim offset will help position the wheel towards the inside of the wheel arch, and if the wheel arch is small, the rims will protrude outward.
So the rim offset is related to the width of the rim, but it should be noted that the choice of rim size depends on the size of the tire... Indeed, the width of the tire must be taken into account where it is in direct contact with the rim.
The rim offset will vary from one car model to the next. It can vary significantly depending on the manufacturer's recommendations. In addition, the manufacturer often leaves a small margin for motorists if they want the rim offset to be different from the recommended one. On average, it will vary from one ten millimeters.
⚙️ Where can I find the rim offset?
The rim offset cannot be read or determined in front of the rim installation guide. Indeed, in order to recognize it, it is imperative to consider the model of your car.
If you want to know what the recommended offset for your car rims is, or the current offset they have if they have not been changed, you can refer to a few items such as:
- Inside the driver's door : This link is next to the recommended tire pressure table for your vehicle.
- Rear part of the fuel filler flap : This area can also contain useful information such as the type of fuel your vehicle is taking and the permissible wheel offset.
- Le service book your car : It contains all the manufacturer's recommendations regarding the maintenance of your vehicle and the replacement of its constituent parts. There will always be a rim offset.
💡 How do I know the rim offset?
The rim offset can also be calculated or measured on your own if you know the width and diameter of your discs, which are expressed in inches. Then you will need to know the exact position of the support surface so that the rim can be attached.
The axis of the rim is in the middle of it: therefore, it is necessary to measure the distance between it and the mounting area. Thus, the amount of offset will vary depending on 2 cases:
- The offset will be zero Whether the seating surface is located exactly in the middle of the rim of your vehicle;
- The offset will be positive if the contact surface is in the center of the rim outside the vehicle.
Therefore, the amount of displacement of the rim will vary depending on the position of the bearing surface. The further it is from the center of the rim, the greater the displacement will be and can reach a significant value up to 20 or even 50 millimeters.
📝 What are the tolerance standards for rim misalignment?
Regarding the legislation, it is obvious that there are tolerance standards for the misalignment of your discs. This also applies manufacturer's warranty when you review, technical control pass or correct handling of your car by your Car insurance.
Generally, allowable rim misalignment ranges from 12 to 18 millimeters... For example, the rim offset may be greater depending on the material of the rims (alloy, sheet metal, etc.).
However, some checks need to be done when you change discs, because if the offset is too great, they can run into friction. stopping support and cause premature wear.
Rim offset is an important concept to know when you want to replace rims if they are damaged, or simply if you want to replace them with a more aesthetic model. In case of doubt, do not hesitate to consult the manufacturer's recommendations or call a specialist in the workshop!
