After exchanging emails with Peugeot in England and France, and checking with the European manufacturer of what turned out to be one piece nuts 505 nuts with a 60deg face but which looked like the ball Nuts, its been made clear that these "washer" nuts are actually 60degree tapered nuts and are not suitable for the ball seated alloy wheels... Wheel fasteners: Understanding the nuts and bolts of wheel clamping - Automotive Service Professional Quote "the two most commonly found seat styles are the tapered (also called conical, or cone) pictured here on the left; and the radiused, or “ball” style. The two styles must never be mixed. The seat profile in the wheel dictates the nut or bolt seat style. If a tapered fastener is installed to a wheel that features radius seats (or if radius style fasteners are installed to a wheel that features tapered seats), proper clamping force cannot be achieved, and the fasteners are sure to loosen." accordingly I have posted the 16 nuts back to the business I purchased the ball-seated 15" alloy wheels and nuts from, and enclosed sufficient funds to pay the return postage ( insured, registered and trackable) for 16 of the ball nuts. Will post up how it all goes. Its costing me an additional $40 in postage both ways - but there you are.
I had started a thread here as well
http://www.aussiefrogs.com/forum/peugeot-forum/116370-505-alloy-nuts-two-types.html