There seems to be a problem. So at the moment I am asking specifically for 240 wheel nuts please.
To explain the little that I "know".
Skandix list studs for the 100, 200 & 1800 (one is genuine Volvo) and different studs for the 700/900. I think that might be definitive that there is an issue.
http://skandix.de/en/spare-parts/sus...heel-stud/552/
EDIT: And this is the Skandix listing for wheel nuts. Also different between 100/200/1800 v. 700/900. http://www.skandix.de/en/spare-parts...l-nut/553/?s=r
And.
It appears that a 1/2" UNF nut will fit an m12 x 1.25 stud, but, only make contact at the edges of the thread. So NI your 240 nuts on a 740 might have been a lucky escape? I don't know. But I have been pointed to this.
http://www.trailersailerplace.com.au...p?f=11&t=13548 It's about a problem with a trailer wheel studs and nuts. The web page AND the comments are interesting.
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