On Mon, 31 Oct 2011 14:04:38 -0700 (PDT), N8N
wrote:

On Oct 31, 4:56Â*pm, micky wrote:
I finally bought the trailer hitch for my Solara and it came with
Â*M10 -1.25 x 30mm bolts. Â* So how come I need to use the 17mm socket
on a 10mm bolt?

SAE bolts aren't this confused.

makes sense to me. The wrench size is the distance across the flats,
the nominal size of the bolt is related to the size of the threads.
SAE works the exact same way. e.g. a 3/8-16 UNC bolt or cap screw
typically requires a 9/16" wrench to tighten.

The only exception that I'm aware of is Whitworth, although I'm sure
that someone will correct me with an even more obscure example.

nate
Whitworth AND BSF used thread size nomenclature for their wrenches
instead of AF size