Jadz928

What Rob said.
However, it may be worth ordering a few 21mm dia washer just in case the area around the hole has opened-up or cracked (as opposed to using a secondary fender-washer).
A close visual inspection should help you understand if you may need this.

Also, make sure to pick up a few extra 'speed clips' just in case some of your's are stripped.

islaTurbine

jpitman2

Note that 6.3-6.4mm is pretty much 1/4" , and 4.8mm will be 3/16", so the washers shouldnt be an issue. Still shaking my head over a Chevy Blazer with an earth strap on the firewall attached with a 10mm headed bolt. No, it wasnt 3/8". Where a common need is satisfied in bulk by a fixing of another measurement regime than your home one, it makes commercial sense to use the cheapest satisfactory solution. I see things like mixes of metric and imperial ball bearings in items from Japan all the time.
jp 83 Euro S AT 57k