Import tyres? Not suitable for German motorway? Dunlop Sport Maxx

Hello guys, I’m looking for a good tire for my DB 600, which is only driven in summer and in dry weather. I came across an extremely cheap offer of a big internet dealer: Dunlop Sport Maxx in 255/45 R18, which is price-wise in the ranks of the Chinese. What makes me stutzig: Dunlop officially does not run this tire in this size in Germany, asked. And the other Internet shops did not offer it either. Older than 2 years he can not The reason for my skepticism is that something like that happened to me at the time on my BMW. It was also Dunlop with a funny name, somehow SP Sport 6000 E or something. The tire was made in South Africa. It ran perfectly, but on the highway so from about 180 he started to become incredibly loud. It rattered like on a sand road. The dealer took it back immediately and I got a SP 01 made in Germany. I guess the tire w ar for this reason not sold in Germany by Dunlop. Speed index was W, but I guess, sometimes, that tires sold abroad, can withstand these speeds, but then get extremely bad running characteristics. One will probably optimize them due to the speed restrictions to a maximum of 130 or 150. My question: do the manufacturers offer special models because of the high speeds in this country? Probably it is better to not sell the tires to buy, isn’t it?