Tyre size for Omega B, built in 1999

Hello, which tyres fit on my Omega B. I thought 195/65 R15 would fit, but the tire workshop says Neee. I would lose the TÜV approval immediately if I went to the TÜV now. Should buy me immediately 205/65 R15 94H. And only those, no others. But I don’t understand that, drive around all the time with 195/65 R15 91T since I bought the car. Has the former seller charred me? Unfortunately in my car bill there is nothing of 195/65 R15 , but only 205/65 R15 9 4H. Here in the forum I always read 195/65 R15 for an Omega B. What’s right now? I now also got the tyre size 195/65 R15 due to the following thread, what now?http://www.motor-talk.de/forum/smallest possible-wheels-and-tire combination-for-omega-b-t2534709.html