Metric Tire Codes vs. Wheel Center Bore
Comparing 2 standards across 14 specifications. 14 key differences identified.
The ISO Metric Tire Code (standardized under ISO 4000-1 and ETRTO conventions, e.g. P225/45R17 91V) is the universal automotive tire sizing nomenclature. Decoding section width in millimeters, aspect ratio sidewall height percentage, internal radial carcass construction, wheel rim diameter in inches, load index, and maximum speed symbol.
The Wheel Center Bore (measured in millimeters to 0.1 mm precision) is the machined center opening on the back of a wheel designed to fit snugly over the vehicle's raised wheel hub snout. Ensuring the wheel is mounted 'hub-centrically' (bearing vehicle weight on the center hub collar rather than the lug bolts), preventing high-speed vibrations.
Specification Comparison Table
14 Parameters| Parameter / Spec | ||
|---|---|---|
|
Standardization
|
ISO 4000-1 / ETRTO (European Tyre and Rim Technical Organisation) / US Tire & Rim Association (TRA) | — |
|
Prefix Designation
|
P: Passenger Car | LT: Light Truck (heavier plies) | ST: Special Trailer | T: Temporary Spare | — |
|
Section Width (e.g. '225')
|
Nominal cross-sectional tire width in millimeters from sidewall to sidewall (225 mm) | — |
|
Aspect Ratio / Profile (e.g. '45')
|
Sidewall section height expressed as a percentage of width (Height = 225 × 0.45 = 101.25 mm) | — |
|
Internal Construction (e.g. 'R')
|
R: Radial ply cord orientation (90° to travel) | D / B: Bias ply / belted bias (historic) | — |
|
Rim Diameter (e.g. '17')
|
Wheel rim bead seat diameter in whole inches (17.0 inches = 431.8 mm) | — |
|
DOT Date Code
|
4-digit oval stamp (e.g. '2422' = manufactured during the 24th week of 2022) | — |
|
Hub-Centric Engineering Function
|
— | Center hub collar centers the wheel with zero eccentricity and supports vehicle radial shear loads |
|
Volkswagen / Audi (VAG MQB)
|
— | 57.1 mm center bore (VW Golf, Jetta, GTI, Audi A3, TT) |
|
Audi / Mercedes-Benz / BMW G-Chassis
|
— | 66.6 mm / 66.56 mm center bore (Audi A4/A6/S4 MLB platform, Mercedes C/E-Class, modern BMW) |
|
BMW Classic (E & F Chassis)
|
— | 72.6 mm (standard BMW hub) | BMW E39 5-Series exception: 74.1 mm |
|
Subaru / Toyota GT86
|
— | 56.1 mm center bore |
|
Honda / Acura / Nissan
|
— | 64.1 mm (Honda/Acura) | 66.1 mm (Nissan/Infiniti) | 60.1 mm (Toyota standard) |
|
Hub-Centric Rings (Spigot Rings)
|
— | Machined aluminum or polycarbonate adapter rings (e.g. 73.1mm aftermarket wheel bore -> 57.1mm VW hub) |