How to Read BMW Wheel Fitment Specs: ET, PCD, Hub Bore Explained

BMW wheel fitment specs look like a foreign language until you understand the three key numbers. Once you do, you can evaluate any wheel for any BMW in about 30 seconds.

PCD: Bolt Pattern

PCD stands for Pitch Circle Diameter. It defines the diameter of the imaginary circle that passes through all the wheel bolt holes. BMW M cars use 5x112 PCD: 5 bolts on a 112mm circle. This is the same pattern across most modern BMW M vehicles. A wheel with the wrong PCD physically cannot be installed. This is the first number to confirm.

ET: Offset

ET (Einpresstiefe, German for press depth) measures how far the wheel mounting face is from the wheel centerline. A positive ET means the mounting face is toward the outside (street side) of the wheel centerline. Zero ET means the mounting face is at the wheel center. Negative ET means the mounting face is inboard of center (the wheel sticks out further).

BMW M cars typically run ET35-ET52 for standard street use. Lower ET numbers push the wheel further outward, improving track width and visual stance. Going too low causes the wheel to protrude beyond the fender edge. Going too high causes the inside of the wheel to contact suspension components.

The G80 M3 runs 275/35R19 rear on ET27 from the factory on 9.5-inch wide wheels. Aftermarket options running ET15-ET22 on wider 10-10.5 inch wheels improve stance and track width meaningfully.

Hub Bore: Center Bore

The hub bore is the diameter of the center hole in the wheel. BMW uses a 66.6mm hub bore across most M car applications. A wheel with a larger center hole requires a hub centric ring to center properly. Without the hub centric ring, the wheel centers on the lug bolts rather than the hub, which can cause vibration at high speed. Quality wheels sized for BMW will include hub centric rings if their center bore doesn't exactly match 66.6mm.

Width and Diameter

Wheel width affects tire fitment. Too narrow and the tire sidewalls bulge outward (poor handling). Too wide and the tire is stretched (aesthetic look some prefer, but degrades handling). The tire manufacturer's fitment guide specifies the appropriate rim width range for each tire size. Always verify before ordering.

Browse wheel options in the G8X collection and ensure fitment specs match your specific chassis before ordering.