I've never seen this before, why would every wheel get a different weight, yet its the same exact tire and wheel. And yup, got vibration at highway speed. These people already pissed me off scratching my wheels.
Have to blame that on design. No one will use sticky weights unless they have no other choice, if it has a lip for hammer-on that's what will be used because it's the easiest form of balancing. Any corrosion or discoloration is the rims fault. Just one of those things.I hate hammer on weights thought because they always ruin the finish on the lip and lead to nasty corrosion over time.
Don't forget that Nankang is headquartered in Taiwan, but much of the manufacturing is now done in Jiangsu China. If you want to find out for sure, just smell them; your nose will instantly tell you if they are made in China. (All rubber products made in China have a very strong and offensive odor.)
I had a set of Chinese tires that came with the Saab on the stock 18" rims. Sport type, don't remember the brand. Went to three different shops and they just wouldn't balance. No visible defects or uneven wear, no broken cords, nothing. Then I found a good used set of quality run-flats (can't remember brand/model) and they balanced perfectly even with stick-on weights.