Wheel cover
Under Regulation (EU) 1009/2010 the tread must be covered from above in the zone from 30° ahead to 50° behind the vertical through the wheel centre. If the tyre sticks out past the fender edge, there is no approval.
Inner clearance
Inside, strut, spring, control arm and brake caliper are the tight spots. Wider wheels with high offset move closer. As orientation keep at least about 5 mm at rest – the inspector checks at full lock and under compression.
Track width
Track change (axle) = 2 × (ET_old − ET_new,effective)
A wider track looks good and changes handling slightly. Certificates limit the permitted widening. The calculator flags values above ±2 % of the stock track as “check” – an orientation value, not a law.
These values drive the calculator. Legal limits are binding, guidelines and orientation values help you assess.
| Rolling circumference vs. stock | -2 % to +1.5 % | Guideline | VdTÜV-Merkblatt 751 |
|---|---|---|---|
| Speedometer lead | 0 to 10 % + 4 km/h, never below real speed | Legal | UN-R39 / § 57 StVZO |
| Rim width for the tyre | Approved range per ETRTO table | Guideline | ETRTO Standards Manual |
| Load index | at least the value in the papers | Legal | § 36 StVZO / COC |
| Speed rating | at least the papers' value (winter tyres: sticker) | Legal | § 36 StVZO / COC |
| Wheel cover | 30° ahead to 50° behind the wheel centre | Legal | VO (EU) 1009/2010 |
| Track widening | check closely above ±2 % | Orientation | Orientierungswert |
| Remaining fender gap | ≥ 5 mm | Orientation | Orientierungswert |
| Remaining strut gap | ≥ 5 mm | Orientation | Orientierungswert |
| Thread engagement | ≥ 1 × thread diameter | Guideline | Faustregel (≥ 1 × d) |
Try it: enter your values in the calculator and see what changes live.
Open calculatorGeneral information without warranty – no legal advice. Vehicle documents, certificates and the inspector are authoritative.