The Rim Dictionary
Confused by "ET45" or "5x112"? Don't know a "Buckle" from a "Bend"? We decode the slang and the science.
Offset (ET)
The distance from the hub mounting surface to the center line of the wheel.
PCD (Pitch Circle Diameter)
The imaginary circle drawn through the center of the bolt holes.
Gutter Rash
Scratches and scuffs on the outer edge of a rim caused by hitting a curb.
Buckle
A deformation in the barrel of the wheel, usually caused by potholes.
Center Bore (CB)
The size of the machined hole in the center of the wheel that fits onto the vehicle hub.
Diamond Cut
A premium finish where a CNC machine removes a thin layer of alloy to create a shiny, rainbow-like reflection.
Spigot Ring
A plastic or aluminium ring used to close the gap between a wheel's center bore and the vehicle's hub.
J-Rating
The width of the wheel in inches, measured between the bead seats.
Rolling Radius
The total circumference of the tyre when inflated.
Split Rims
Wheels constructed from 2 or 3 separate pieces bolted together.
Forged Wheels
Wheels pressed from a solid block of aluminum under immense pressure.
Flow Formed
A hybrid manufacturing process where the barrel is spun and stretched while hot.
Run-Flat Tyres
Tyres with reinforced sidewalls that can drive for a limited distance after a puncture.
TPMS (Tyre Pressure Monitoring System)
Electronic sensors inside the wheel that monitor air pressure in real-time.
Hellaflush
A fitment style where the wheel is perfectly flush with the fender, often requiring extreme camber.
Tyre Stretch
Fitting a narrower tyre onto a wider rim (e.g., 205 width on a 9J rim).
Wobble Bolts
Special bolts with a floating collar that allow fitting slightly different PCDs.
Wheel Spacers
Metal discs placed between the hub and the wheel to push the wheel outwards.
Camber
The vertical angle of the wheels compared to the road surface.
Lak Peel (Lacquer Peel)
When the clear coat on a diamond cut wheel starts flaking off.
Bead Seat
The area on the rim where the tyre seals against the wheel.
Flat Spot
A localized flattened section on the rim, usually on the inner lip.
Wheel Weights
Small lead or zinc weights stuck to the barrel to balance the wheel.
Multi-PCD
Wheels drilled with two sets of bolt patterns (e.g., 5x100 and 5x114).
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