Thread is 12mm dia and 1.5 mm pitch. But that's not enough info since there are different shapes to the tapered seat. Honda's is a curve shape, not a straight taper. Some aftermarket wheels uses cylinder shape. Must match lug nuts to the wheel seats.
Originally posted by krazik-s2k: My manual is MIA,
The Honda seat is spherical rather than conical which is much more common. This is why there is such a limited choice in lug nuts for the stock wheels.
I would really like to use the black Mugen nuts I have but they are for the conical seat. I have shopped numerous places for nuts and locks with limited luck. Therefore I am using the stock nuts with the Honda Europe locks.