There is news again! After a few weeks of research I found my ideal rim / tire combination. I don't just buy something, I do my homework first ... Otherwise you will not buy a Skoda diesel!
Like I said before, I was looking for lightweight forged audi rims, like the first generation A2 and A3. It put's 12 lbs on the scale. There isn't a lighter 15" rim that fits my car, or yes there are, having to put down a 4-digit number for professional racing rims. But It turns out that even those Audi rims are quite rare and extremely expensive on the second hand market. People dare to ask $ 350 for a set of 20 years old. That just doesn't work for me. So I went looking for a set with signs of wear and totally worn tires so I could negotiate. And succeede. I have even been able to resell those worn tires .
Secondly, the tires. What was important to me of course is low rolling resistance. The most important thing, however, was a good grip in dry and wet conditions. Especially because I go to a more narrow tire, so less contact with the road. Ideally it would also have a slightly larger diameter so that the RPM's can be lowered at high speed. The largest (common) size with the narrowest tread for the 15" rim is 175/65. The tire with the best grip (A-rating) in that size is the Dunlop Sport Fastresponse. The score for RR is an average C, but in an independent Dutch tire test it scores as well as an A-rated tire. Also the weight of that one is quite low opposite other brands, being 15 lbs.
After some research I found (new) demo tires for half the price, including placement.
It has got an interesting asymmetrical tread design, rather different than that of LRR premium tires such as Conti EcoContact or Michelin Energy Saver.