Slippery tyres

Good day men. Wow, this gave me a jolt. I have had 11 BMWs'. My current chariot is a 530i champagne, have had this car for 3 years. Last week I put a pair of Antyres on the rear. 265.35 ZR 18 as specified in the book. Driving to work the same way as I have for 24 years early in the morning. The back end slid about 2 meters, cars speed 30 mph, I have ABS and DSC, this has never happened before. There is no doubt at all in my mind that these are frankly dangerous. The car has never missed a beat ever, it is meticulously maintained and mint. Just out of respect for my fellow humans I just joined this site. Honestly, I drove to Tescos today for petrol on dry roads, the rears squeal and slip, im not a nutter im 56 and take care on the roads. Now when I arrived home I typed in Antyre reviews.There is something fundamentally wrong with the design of these. I telephoned a fellow I know and use who owns and runs a large garage this afternoon. Told him I need to take these off the car asap, and I mean that. I bought these from e bay for £90.00 each, advertised as used for 1 week; now I know why.
No doubt at all the best are either Michelin, the two brothers who started the company 100 years ago started with cycle tyres and progressed. They bought Citroen after Andre Citroen went bust due to his gambling debts. Next for me come Continental, then Goodyear, then Uniroyal and Bridgestone, Dunlop equal. At my age one thing I have learned in life; YOU GET WHAT YOU PAY FOR; no matter whether it is a biro or toilet paper. I cannot afford 2 new tyres really this month, but family first and wont allow them harm.
To prove my sincerity and worry, if any of you would like these 'as new tyres fitted last week' you may have them free; collection from Portsmouth. I would rather you didn't but perhaps top gear will collect them and demonstrate. Take Care be safe great site