What Does ET Mean on Wheels?
If you’ve ever looked at a wheel specification and seen something like ET35, ET45, or ET20, that “ET” number is referring to the wheel offset.
ET comes from the German word “Einpresstiefe,” meaning “insertion depth.”
In simple terms, it tells you how far the wheel mounting face sits from the centre line of the wheel.
But what really matters is this:
- ET controls how far the wheel sits in the arch or out toward the arch
- It directly affects stance, clearance, rubbing, and legality
After 15+ years fitting wheels, we can say confidently — most fitment issues start with misunderstanding ET.
How ET Works in Real Fitment
The ET number is measured in millimetres and works like this:
- Higher ET number (e.g. ET45) → wheel sits further inside the arch
- Lower ET number (e.g. ET20) → wheel sits further outside the arch
This is where a lot of confusion happens.
A common mistake is thinking lower ET pushes the wheel inward — but it’s actually the opposite.
That misunderstanding leads to:
- Wheels sticking out too far
- Tyre rubbing on arches
- Unsafe or illegal fitment in some countries
Why ET Matters So Much
ET is not just a styling number — it affects how the entire wheel setup behaves.
Key areas affected by ET:
- Arch clearance
- Suspension clearance
- Steering response
- Tyre wear
- Brake caliper clearance
- Legal fitment in certain regions
Even a 5–10mm change in ET can completely alter how a wheel fits a car.
Real-World Fitment Problems Caused by ET
In our experience, most ET-related issues fall into a few categories:
Wheels sticking out too far
- Happens when ET is too low for the car
- Can cause stone chipping and arch damage
- May be illegal if tyre protrudes beyond the bodywork
Rubbing on lowered cars
- Very common on coilover setups
- ET too low combined with wide tyres causes arch contact
- Especially noticeable under load or cornering
Wheels sitting too far inside
- Common when customers play it “safe” with high ET
- Can look weak or OEM-unbalanced
- Often fixed using spacers
ET vs Wheel Spacers (Important Real-World Fix)
Wheel spacers are often used to adjust ET without changing wheels.
For example:
- ET45 wheel + 15mm spacer = effective ET30
This is a normal and widely used method in professional fitment.
However:
- ✔ Hubcentric spacers are strongly recommended
- ✔ Correct torque and fitting is essential
- ❌ Cheap spacers can cause vibration or safety issues
Used properly, spacers are a safe and effective fitment tool.
How We Actually Choose the Correct ET
We never choose ET based on guesswork.
We always check:
- Vehicle make, model, and year
- Brake size and any upgrades
- Wheel width
- Tyre size
- Suspension setup (standard or lowered)
- Customer goal (safe daily, flush, or aggressive stance)
For example:
- BMW models often tolerate more aggressive fitments
- VW Golf R requires more precision to avoid rubbing
- Audi A4 varies heavily depending on suspension
- Ford Transit Custom needs careful load and clearance balance
- Range Rover allows larger wheels but needs correct tyre sizing
There is no universal ET that works for every car.
Common Customer Misunderstanding About ET
One of the biggest misconceptions we see:
“Lower ET just means a nicer fitment”
In reality, lower ET:
- Pushes wheels outward
- Increases arch stress
- Raises risk of rubbing
- Can affect legality depending on location
ET is not about “better” or “worse” — it’s about correct balance for the setup.
Final Advice: Don’t Choose ET Blindly
ET is one of the most important parts of wheel fitment, yet it’s often chosen incorrectly online without proper guidance.
The safest approach is always:
- Match ET to your exact car setup
- Factor in tyres, suspension, and brakes
- Get professional advice before buying
Expert Tip
After years of fitting wheels, one rule always applies:
The perfect ET is the one that fits your real-world use — not just what looks good in photos.