What is the offset on front and rear wheels?
The offset of a wheel is the distance from the hub mounting surface to the wheel’s centerline, measured in millimeters. On many cars the front and rear offsets are the same, but some vehicles—especially those with staggered or performance setups—use different offsets on each axle.
Understanding wheel offset
Wheel offset is a key specification that determines how far a wheel sits in relation to the suspension and fender lines. It is usually expressed as ET (Einpresstiefe, a German term) followed by a number in millimeters. Positive, zero, or negative values describe how far the mounting surface is from the wheel centerline and thus how far the wheel sits toward the inside or outside of the vehicle.
Types of offset
Different offset values change the wheel’s fitment and stance. Here are the common categories you’ll encounter:
- Positive offset: The mounting surface sits toward the outside of the wheel, which moves the wheel’s centerline inward toward the vehicle. This typically yields a wheel that sits closer to the suspension and fender.
- Zero offset: The mounting surface aligns with the wheel’s centerline, placing the wheel’s center evenly with the hub center.
- Negative offset: The mounting surface sits toward the inside of the wheel, pushing the wheel’s centerline outward and often yielding a wider track and a more pronounced stance.
In practice, most street cars use positive offset wheels, with a few exceptions for performance or aftermarket builds that aim for wider track or a flush look.
Front vs rear offsets
In many cars, the offset is the same for both the front and rear wheels. However, some vehicles use different offsets on each axle to optimize handling, clearance, and drivetrain layout. This is common on staggered setups where rear wheels are wider or mounted with a different offset to achieve a desired stance or performance characteristic.
Why offsets differ between axles
The reasons for different front/rear offsets include clearance for larger brake calls, accommodating wider rear tires, and achieving a specific track width to influence handling balance. When offsets differ, it’s essential to verify that both axles’ wheels remain within the manufacturer’s recommended fitment to avoid rubbing or alignment issues.
How to determine the offset for your wheels
To know the exact offset for each wheel on your vehicle, follow these steps:
- Check the manufacturer’s specifications for your vehicle and the wheel you plan to use—these often list front and rear offset values separately.
- Inspect the wheel itself for a stamped ET value, typically found on the rim’s backside or the spoke area (e.g., ET35).
- Consult the wheel manufacturer or retailer for OEM-equivalent offsets and compatibility with your vehicle’s hub bore and bolt pattern.
- If you’re unsure after checking documentation, consult a qualified shop or automotive technician to verify fitment on both axles.
Understanding and matching offset is crucial for correct alignment, steering feel, brake clearance, and tire fitment. Mismatched or inappropriate offsets can cause rubbing, contact with brake components, or steering interference.
Practical considerations for offset choices
When selecting wheels, consider both front and rear offsets (and any potential stagger) in relation to suspension travel, fender clearance, and the vehicle’s track width. If you’re contemplating aftermarket wheels or spacers to adjust fitment, factor in potential changes to handling, wear, and safety, and seek professional guidance to ensure safe installation.
Summary
Wheel offset measures how far the mounting surface sits from the wheel’s centerline, in millimeters. Front and rear offsets can be identical on many cars, but some models use different values to optimize clearance or stance. Always verify exact front and rear offsets from official specifications or the wheel manufacturer, and ensure fitment across both axles to maintain safe handling and clearance.
