PCD, offset, OEM, ceramic pads β auto parts come with a lot of jargon. Here’s a plain-English glossary so you can shop with confidence.
New to car parts? These are the terms you’ll see most often, explained simply.
PCD (Bolt Pattern)
The Pitch Circle Diameter β the number of wheel bolts and the diameter of the circle they form (e.g. 4×100). Your mags must match your car’s PCD. See our PCD guide.
Offset
How far a wheel’s mounting face sits from its centerline. The right offset gives proper clearance and stance; the wrong one causes rubbing.
OEM
Original Equipment Manufacturer β parts that match what your car came with from the factory.
Aftermarket
Parts made by companies other than your car’s manufacturer. Quality ranges from budget to premium β brand and material matter most.
Ceramic Brake Pads
Brake pads made with ceramic compounds β quiet, low-dust, and long-lasting. Ideal for daily driving. See ceramic vs semi-metallic.
Semi-Metallic Brake Pads
Brake pads with metal content for strong bite and heat resistance β great for heavy or spirited driving, but noisier and dustier.
Brake Shoe
The curved friction component in drum brakes (often on the rear of pickups and older cars), versus pads used in disc brakes.
DRL
Daytime Running Lights β lights that stay on during the day for visibility and a modern look.
Aspect Ratio
In a tire size like 185/65 R15, the 65 is the aspect ratio β the sidewall height as a percentage of width. See how to read tire size.
Mags / Alloy Wheels
Lightweight wheels made from aluminum or magnesium alloy β better looks and performance than steel. Browse our mag wheels price list.
Still have a question?
Message us your car and what you’re trying to fix β we’ll translate the jargon and recommend the right part.