Offset and what's correct for the 80's aside...
The original AMG history seems to have started with whatever wheels were used on the 1960's c111 concept car, which were apparently also used on the AMG car that started it all, the red pig. One note on the wheels and their 10,12x15 size here: http://mint2me.com/2013/05/14/outrag...3-amg-replica/
If you take a close look at the wheels shown here, ironically, they look more like ronal r9 than the ATS AMG wheels. http://fabwheelsdigest.blogspot.com/...-race.html?m=1
The AMG (gen1 ATS) wheel was apparently designed in 1979 and I believe it didn't hit the general AMG catalog until a few years later. The ATS wikipedia page shows that the company is apparently most famous for this often copied wheel. https://en.m.wikipedia.org/wiki/ATS_(wheels
I assume that AMG was the first one to come up with this design in 1979, and can't find any reference to when the Ronal R9 wheel was first designed. It was however used on many different brands including BMW and Ford Saleen around 1986.
In my opinion, there are several copies of the ATS AMG wheel, like the "Penta" brand, Melber, the identical Taiwan made I branded copies, and even more I think that seem to be so similar that they must have been copying. The Ronal R9, however, even though it is quite similar, it looks much more like the C111 and wheel that was used by AMG on the car that started it all.
It is interesting to note that the German company, Ronal was in business when both the C111 and Red Pig were built, but I can't find any reference as to who made the wheels on these cars.
I have often assumed that Ronal R9 were produced before the ATS wheels were and possibly used on early AMG tuner cars. However, it seems that Rial N wheels (although quite heavy) were often used on early AMG cars.
In the end, does it matter? Probably not, at least as long as it's clear that nobody is trying to fleece anyone else.