Alloy Wheel – Wheel manufactured from aluminium or magnesium alloys, typically lighter than steel.
Aluminium Wheel – Wheel made primarily from aluminium alloy, usually cast or forged.
Anodizing – Electrochemical surface treatment improving aluminium corrosion and wear resistance.
Axial Runout – Side-to-side deviation of a rotating wheel, measured in millimetres.
Backspacing (BS) – Distance from the wheel mounting face to the innermost wheel edge.
Balancing – Correcting uneven mass distribution to minimise vibration during rotation.
Balancing Weights – Small weights attached to a wheel to correct imbalance.
Barrel – Cylindrical section of the wheel supporting the tyre.
Bead – Reinforced inner edge of a tyre that seats against the wheel rim.
Bead Seat – Wheel surface where the tyre bead rests and seals.
Beadlock Wheel – Wheel using a mechanical ring to retain the tyre bead at low pressures.
Bolt Circle – Imaginary circle passing through the centres of the wheel bolt holes.
Bolt Pattern – Number and arrangement of wheel mounting holes.
Bolt Seat – Contact surface where a wheel bolt secures the wheel.
Bore Diameter – Diameter of the wheel’s central mounting hole.
Cast Wheel – Wheel manufactured by pouring molten metal into a mould.
Centre Bore (CB) – Diameter of the central opening that fits over the vehicle hub.
Centre Cap – Decorative or protective cover fitted to the wheel centre.
Centreline – Imaginary plane dividing the wheel width into equal halves.
Centrelock Wheel – Wheel secured by a single central locking nut.
Concave Wheel – Wheel design with spokes recessed towards the centre.
Conical Seat – Tapered bolt or nut seating surface, commonly 60 degrees.
Corrosion Resistance – Ability of a wheel or finish to resist environmental deterioration.
Curb Rash – Cosmetic damage to the wheel edge from contact with a kerb.
Deep Dish Wheel – Wheel with a pronounced outer lip and recessed centre.
Diameter – Nominal wheel size measured across the tyre bead seats, in inches.
Directional Wheel – Wheel designed with a specific rotational or visual orientation.
Dish – Depth of the wheel’s visible outer lip.
Dual Drilling – Wheel manufactured with two different bolt patterns.
Dual Wheel Fitment – Two wheels mounted side by side on one hub, common on trucks.
Dynamic Balancing – Balancing method correcting mass imbalance across two planes.
ET (Einpresstiefe) – German designation for wheel offset, expressed in millimetres.
Effective Offset – Resulting offset after fitting a wheel spacer or adapter.
Exposed Lug Nuts – Wheel fasteners visible rather than concealed by a centre cap.
Fitment – Compatibility of a wheel with a vehicle’s mounting and clearance requirements.
Flow Forming – Manufacturing process using rollers to shape and strengthen a cast wheel barrel.
Forged Wheel – Wheel produced by compressing metal under high pressure for improved material properties.
Front spacing – Distance from the wheel mounting face to the outermost wheel edge.
Full-Face Wheel – Wheel design where the visible face extends close to the outer rim edge.
Galvanic Corrosion – Corrosion caused by contact between dissimilar metals in the presence of an electrolyte.
Gross Axle Weight Rating (GAWR) – Maximum permitted load carried by an axle.
Gross Vehicle Weight Rating (GVWR) – Maximum permissible total operating weight of a vehicle.
H2 (Double Hump) – Rim profile featuring two bead-retaining safety humps.
Hard Anodizing – Durable anodized surface treatment improving hardness and corrosion resistance.
Hub – Vehicle component supporting the wheel and connecting it to the axle.
Hub Bore – Central opening in the wheel that fits over the hub.
Hub Centric Wheel – Wheel centred on the vehicle hub through a matching centre bore.
Hub Centric Ring – Adapter ring used to match a larger wheel centre bore to a smaller hub.
Hub Centric Spacer – Spacer incorporating a centring lip to maintain hub-based wheel alignment.
Inboard Clearance – Space between the inner wheel or tyre and nearby suspension or body components.
Inner Barrel – Inner cylindrical portion of the wheel, often critical for brake clearance.
Inset – Positive wheel offset, where the mounting face is outward of the wheel centreline.
Installation Torque – Specified tightening force applied to wheel bolts or nuts, expressed in Nm.
J Profile – Standard passenger-car rim flange contour designation.
JJ Profile – Alternative rim flange contour commonly found on certain SUV and 4×4 wheels.
Knurling – Textured wheel bead-seat surface designed to reduce tyre rotation on the rim under high torque.
Load Capacity – Maximum weight a wheel is designed and rated to support.
Load Rating – Certified or declared maximum permissible load per wheel, usually in kilograms.
Lug Bolt – Threaded fastener securing the wheel directly to the hub.
Lug Nut – Threaded nut securing a wheel to a hub-mounted stud.
Lug Centric Wheel – Wheel centred primarily by its mounting fasteners rather than the hub.
Lug Hole – Opening through which a wheel bolt or stud passes.
Magnesium Wheel – Lightweight wheel manufactured from magnesium alloy.
Maximum Wheel Load – Highest permissible load supported by an individual wheel.
Monoblock Wheel – Wheel manufactured as a single structural piece.
Mounting Face – Flat wheel surface contacting the vehicle hub.
Multi-Piece Wheel – Wheel assembled from two or more separate components.
Multi-Fit Wheel – Wheel designed to accommodate multiple vehicle bolt patterns.
Negative Offset – Mounting face positioned inward of the wheel centreline.
Nominal Diameter – Designated wheel diameter measured at the tyre bead seats.
Nut Seat – Shaped contact area between a lug nut and the wheel.
OE (Original Equipment) – Components supplied as part of the vehicle’s original specification.
OEM (Original Equipment Manufacturer) – Manufacturer producing components for original vehicle equipment.
Offset – Distance between the wheel centreline and mounting face, measured in millimetres.
Outer Lip – Visible outer edge of the wheel rim.
Outboard Clearance – Space between the outer wheel or tyre and the fender or bodywork.
PCD (Pitch Circle Diameter) – Diameter of the circle passing through the wheel mounting hole centres.
PCD 5×114.3 – Five mounting holes arranged on a 114.3 mm diameter circle.
PCD 6×139.7 – Six mounting holes arranged on a 139.7 mm diameter circle.
Plus Sizing – Increasing wheel diameter while selecting tyres to maintain a similar overall rolling diameter.
Positive Offset – Mounting face positioned outward of the wheel centreline.
Powder Coating – Durable coating applied electrostatically and cured using heat.
Pressure Casting – Casting process using controlled pressure to improve mould filling.
Profile (Rim) – Cross-sectional geometry of the wheel rim and bead-seat area.
Reverse Mount Wheel – Wheel designed for tyre installation from the rear side.
Rim – Outer portion of the wheel that supports and retains the tyre.
Rim Diameter – Diameter measured between opposing tyre bead seats.
Rim Flange – Raised edge of the rim retaining the tyre bead.
Rim Protector – Tyre sidewall feature extending beyond the wheel flange to reduce minor contact damage.
Rim Width – Distance between the inner faces of the two bead-retaining flanges.
Rolling Diameter – Overall diameter of the tyre and wheel assembly.
Runflat-Compatible Wheel – Wheel designed to accommodate a specified runflat tyre or insert system.
Safety Hump – Raised rim feature helping retain the tyre bead during pressure loss.
Single-Piece Wheel – Wheel manufactured as one complete structural unit.
Spacer – Component installed between hub and wheel to move the wheel outward.
Split Rim – Wheel or rim assembled from separable sections.
Spoke – Structural element connecting the wheel centre to the outer rim.
Steel Wheel – Wheel manufactured from formed and welded steel components.
Stud – Threaded shaft attached to the hub onto which a wheel is secured.
Stud Pattern – Number and arrangement of mounting studs, equivalent to bolt pattern.
Tapered Seat – Conical contact surface used by certain wheel bolts and nuts.
Thread Pitch – The distance or spacing between the threads of wheel stud or bolt. It dictates how tight or loose the spiral groove is.
Thread size – The outer diameter of the thread.
TPMS (Tyre Pressure Monitoring System) – Electronic system monitoring tyre pressure.
Track Width – Lateral distance between the centre planes of wheels on the same axle.
TRAK+ Spacer – H&R wheel spacer product range used to increase track width.
Two-Piece Wheel – Wheel assembled from two principal structural components.
Tyre Bead Seat – Wheel surface against which the tyre bead seals.
Tyre Rotation on Rim – Circumferential movement of the tyre relative to the wheel under load.
Undercut Spoke – Spoke design with material removed behind the visible face to reduce weight.
Unsprung Mass – Weight of components not supported by the suspension springs, including wheels and tyres.
Valve Hole – Opening in the rim for the tyre inflation valve.
Valve Stem – Component allowing tyre inflation and pressure retention.
Wheel Adapter – Component allowing a wheel with a different bolt pattern or mounting arrangement to fit a vehicle.
Wheel Alignment – Adjustment of suspension geometry affecting wheel angles and vehicle handling.
Wheel Balance – Distribution of mass around the wheel and tyre assembly.
Wheel Clearance – Available space between the wheel and surrounding components.
Wheel Diameter – Nominal rim diameter, normally expressed in inches.
Wheel Fitment – Combination of dimensions and specifications determining vehicle compatibility.
Wheel Offset – Position of the mounting face relative to the wheel centreline.
Wheel Spacer – Precision component used to increase the distance between the wheel and hub.
Wheel Stud Conversion – Modification replacing wheel bolts with studs and nuts.
Wheel Width – Distance between rim bead-seat flanges, expressed in inches.
Widebody Fitment – Wheel specification intended for vehicles with extended fenders or bodywork.
X-Factor – Wheel spoke clearance available for the brake caliper beyond the mounting face.
X-Factor – Wheel spoke clearance available for the brake caliper beyond the mounting face.
Zero Offset (ET0) – Wheel mounting face aligned exactly with the wheel centreline.