32mm or a 1 1/4 inch will work.

 

1-1/4 in. works just fine and I have been using one for years on my FZ1, and now my R1.
1-1/4 in. works out to 31.75 mm. Put it on the nut and you will see it fits perfect with almost no play. snapon lists a socket with both sizes on it. The guys on the FZ1 site claim that the 1-1/4 in. socket fits better as the 32mm is too loose.

 

1 1/4" is not the same as 32mm, stick with the metric socket :fact

 

I've used 1-1/4" as well without problems. I also have two 32mm sockets..I just grab what's handy. All work equally well.

1-1/4" / 32mm seem to be a standard car axle nut size as well!