Wheel sizes, stud patterns (PCD) and offsets explained

Stud pattern (PCD)

• 4x100: many older small cars (older Vauxhall, Honda, Renault and VW models among them).
• 4x108: older Fords, Peugeots and Citroëns.
• 5x108: most Fords from the Mondeo and later Focus on, Volvo and many newer Peugeots and Citroëns.
• 5x112: VW, Audi, SEAT, Skoda, Mercedes, and newer BMW and Mini models.
• 5x114.3: most Japanese and Korean cars (Toyota, Honda, Nissan, Mazda, Hyundai, Kia).
• 5x120: most BMWs before about 2018, and some Vauxhalls and Land Rovers.

The PCD (pitch circle diameter) is written as the number of studs or bolts times the diameter of the circle they sit on, in millimetres: 5x112 means five bolts on a 112 mm circle. It has to match exactly. A wheel that is 1 or 2 mm out may bolt on but will never sit true, and can work loose.

Centre bore, offset and width

• Centre bore: the hole in the middle that locates the wheel on the hub. It must be the same as your hub or bigger. If it's bigger, plastic or alloy spigot rings take up the gap.
• Offset (ET): how far the mounting face sits from the middle of the wheel, in millimetres. ET45 sits further in than ET35. Stay within about 5 mm of your car's original offset or the tyre may rub on the arch or the suspension.
• Width and rim size: 7Jx17 means 7 inches wide with a 17 inch rim. Bigger rims need lower-profile tyres to keep the same overall size.

Reading a tyre size

A tyre marked 205/55 R16 91V is 205 mm wide, its sidewall is 55% of that width, it fits a 16 inch rim, 91 is the load rating and V the speed rating. Match your car's load rating or go higher. The DOT code ends in four digits giving the week and year it was made (2421 is week 24 of 2021): avoid tyres much over six years old even with good tread. The legal minimum tread in the UK is 1.6 mm across the middle three quarters of the tyre.

Bolts, nuts and locking keys

• Wheel bolts and nuts have a seat that matches the wheel: tapered (60° cone) on most cars, rounded (ball or radius) on many VW, Audi, Mercedes and Honda wheels. The wrong seat lets the wheel work loose, so use the bolts made for that wheel.
• Bolt length matters too: alloy wheels are usually thicker than steel ones and need longer bolts.
• Ask the seller whether the locking wheel nut key comes with a used car's wheels. If you've lost yours, the number on the key's box or the key itself lets a dealer order a new one.

Checking used wheels before you buy

Look for cracks, buckles and repaired kerb damage on the inside of the rim, not just the face, and ask whether it holds air. The PCD, offset and size are usually cast on the back of a spoke. Give the seller your registration and they can confirm the fitment. Search for wheels, browse by make, or read how to find the right used part.