Wheel offset (ET) guide
What is wheel offset (ET)?
Wheel offset (ET from German Einpresstiefe = insertion depth) is the distance in mm from the wheel's mounting face to its centreline. Positive ET: mounting face is closer to the outside (most modern cars). Zero ET: mounting face is at the centreline. Negative ET: mounting face is closer to the inside (wide stance, off-road). The correct ET affects steering, clearance and bearing load.
- Wheel offset (ET from German Einpresstiefe = insertion depth) is the distance in mm from the wheel's mounting face to its centreline.
- Positive ET: mounting face is closer to the outside (most modern cars).
- Zero ET: mounting face is at the centreline.
FAQ
- What is wheel offset (ET)?
- Wheel offset (ET from German Einpresstiefe = insertion depth) is the distance in mm from the wheel's mounting face to its centreline. Positive ET: mounting face is closer to the outside (most modern cars). Zero ET: mounting face is at the centreline. Negative ET: mounting face is closer to the inside (wide stance, off-road). The correct ET affects steering, clearance and bearing load.
- What should I verify before using this information?
- Use TireFitLab values as a sizing reference, then verify the vehicle handbook, tire placard, rim compatibility, load rating, and physical clearance before fitting.
Offset types at a glance
| ET range | Type | Typical vehicles | Notes |
|---|---|---|---|
| ET 40–55 | Positive (high) | FWD compacts, modern sedans | Flush or tucked wheels, minimal overhang. |
| ET 20–40 | Positive (moderate) | Most AWD/RWD cars & SUVs | Balanced stance, stock look. |
| ET 0 | Zero | Classic muscle cars, some trucks | Wheel face exactly at centreline. |
| ET −10 to −30 | Negative | Off-road trucks, stance builds | Wide stance; check arch clearance. |
| ET −30 and below | Negative (extreme) | Dedicated off-road / show | Spacers or adapters often needed. |
ET vs backspacing
ET is measured in millimetres from the mounting face to the centreline. Backspacing (used more commonly in North America) is the distance from the mounting face to the inner lip of the wheel. The relationship:
Backspacing (mm) = (rim width mm / 2) + ET
Example: a 225mm (8.86") wide wheel with ET 38 → backspacing = 112.5 + 38 = 150.5 mm (≈ 5.9").
How ET affects fitment
- Too high ET (too positive) — wheel sits deep inside the arch. Inner sidewall may rub suspension or brake callipers. Rare on stock setups.
- Too low ET (too negative) — wheel protrudes outward. Outer sidewall may rub the wheel arch liner. Increased scrub radius stresses steering geometry and wheel bearings.
- OEM ET ± 5–8 mm is the safe range for most daily-driven cars without recalibrating ADAS or alignment.
How to read an ET stamp
The ET value is cast or stamped on the back of most alloy wheels, typically near the centre bore: ET38 or ET +38. Negative values appear as ET-15. Some manufacturers print it as Offset 38 or use the French abbreviation IS (Inset).
More tools
- Wheel offset (ET) decoder
- Bolt pattern guide
- Rim diameter guide
- Plus sizing guide
- Tire & wheel reference guides
Seasonal check
Planning a long summer drive?
Use the budget and running-cost tools before a trip, especially if the current tyres are worn or the replacement size changes diameter.
What changed
- Reviewed deterministic geometry, load/speed references, sitemap inclusion and localized page shell.