Tires are 1 year old, but they are in perfect condition, they haven't been driven much. Bought them as a set of 4 - brand new. The only difference is that I put 245s on the front, instead of 235s. If they were old, for sure the problem will be smaller, as on sliperry surface the wheels are not shaking, but I don't think they are causing this.
About the other things - the first time they just checked the parts (rack, hose, pump - everything has been stripped down and carefully inspected. The second time we just have taken the same parts from a different car and put them to mine. Both time without any result.
Suspension has been checked several months ago and every faulty part has been replaced. They have checked it again now though, but nothing again.
This really seems like a nightmare.