Hello everyone! This is my first post so I'll try to do it right 😕 

I bought a 2009 Ford Focus 2 with the 1.8 TDCI engine that has 200,000 km on the clock. I noticed some vibrations in the steering wheel on the highway, so I immediately thought of getting my tires balanced. Since the vibrations occurred around 100 km/h, someone suggested it might be the rear tires, but balancing the rear didn't change anything. So, I balanced the front tires, which slightly improved the situation, but the vibrations were still there. I took it to a garage nearby, and they suggested it might be the engine mounts (right and bottom ones). They estimated it would cost around 450 euros for the part (Corteco). Not having the means at the time, I waited a few weeks before ordering the right engine mount from PROCODIS and the bottom one from CORTECO online. The issue persisted, with vibrations during acceleration at low speeds, and this time, the whole car was shaking. I realized that the new right mount might be too rigid, so I reverted to the old one. Then, another garage suggested that the front tires seemed suspicious, so I decided to get new ones and also check the balancing of the rear tires. I found out that the rear tires were no longer balanced, but even after changing both front tires and checking all four multiple times, the problem is still lessened but equally bothersome.

My questions:

Could the suspected worn-out dual-mass flywheel be the culprit? If so, I'm considering either Luk or Sachs. Which one should I go for ? 

Should I reconsider the engine mount and go for Corteco or another brand, or could it be something else entirely?

I'm a beginner in mechanics (I've done quite a bit of research on the topic, but I can't figure out what I'm missing), so I'm open to any suggestions!

Thanks in advance!

P.S. I'm based in France.

Probably too late for you but after wheel balancing, I would have looked at aging control arm bushes and ball joints, track rod ends and ball joints and drop links. Slack there would feed into the steering (and show itself in tyre wear, the tyres showing the effects, not being the cause). Had a similar problem diagnosed by the MOT which now dealt with (2008 1.8 TDCI). New control arms, track rod ends and drop links have sorted it.