Smart Forfour wheel bolt & nut sizes
The Smart Forfour (2003 on) uses M12x1.5 wheel fixings with a 60° taper seat and a 21mm hex or 17mm hex. It has 4 per wheel, so a full set is 16. Check the table below for the exact fixing for your year and wheel type.
Last updated 2 October 2026
Thread
M12x1.5
Seat
60° taper
Hex size
21mm hex / 17mm hex
Strength
Class 8 / Class 10.9 (300)
Sizes by year and wheel type
| Image | Model code | Wheel type | Thread | Length | Seat | Hex size | Finish | Strength |
|---|---|---|---|---|---|---|---|---|
| 2003–2008 4 per wheel | ||||||||
| 454 | Steel & Alloy Wheels | M12x1.5 | 42mm | Head Ø 18 | 14.3mm spline | Zinc | Class 10.9 |
| 454 | Steel Wheels | M12x1.5 | – | 60° taper | 21mm hex | Yellow Zinc | Class 8 |
| 2014 on 4 per wheel | ||||||||
| 453 | Steel Wheels | M12x1.5 | 24mm | 60° taper | 17mm hex | Zinc | Class 10.9 (300) |
A dash in the length column means no length is listed for that fixing. Not sure which wheels you have? Steel wheels usually have a plastic trim cover over them.
Locking wheel keys for the Smart Forfour
Lost or damaged your locking wheel key? Find a replacement for your Smart.
Common questions
What size are Smart Forfour wheel bolts?
Smart Forfour wheel fixings are M12x1.5 with a 60° taper seat and a 21mm hex or 17mm hex.
How many wheel bolts does a Smart Forfour need?
4 per wheel, so 16 for a full set of four wheels.