Wobbly Touran!

I have a 2008 2.0 TDi DPF Sport Touran, which I've owned since 2012. Since buying it I've noticed it's very wobbly at speeds over 50 mph & can get quite unstable. I noticed not long after buying it that the rear tyres were stepped, so replaced them. This solved the problem at first, but more recently the wobble has come back worse. The tyres are no longer stepped and look ok.

The wobble gets worse the faster you go, but only happens when the road surface is uneven. I drive to work the same way every day & on the same stretch of motorway I get the wobble, which stops when the road is smoother. When I use my wife's Golf, you don't get the same feeling on the same stretch.

I've also noticed that when the weather is warmer, when turning right only, there is a creaking noise coming from the offside wheel. It's been into the garage a few times for this, but no fault can be found. On top of that I've noticed the inside edge of both front tyres wear more quickly than the rest of the tyre.

Could this his all be linked? I've checked all springs & shocks & they seem fine. The alignment has been checked many times at different garages.

Are Tourans naturally wobbly as they are higher than most cars?

Just a thought here but have you used the tyre repair fluid on any of your current tyres? I've come across a Touran with a similar problem. Tried balancing the tyres and couldn't get one of them to balance. When the tyre was removed from the rim repair fluid came pouring out. No further issue once the fluid was removed.

Thinking you mean wobble as the car drifting side to side and you having to correct steering, rather than rolling from side to side ? Has the stretch of motorway it happens on, got tramlines in it from the HGV's ?
When you say you've had the alignment checked did they just check the front tracking or do a 4 wheel alignment, as the rear wheel toe is adjustable via eccentric bolts on the lower arm, camber is also adjustable. It could be rear toe angle is out on one or both sides, steering the car from the rear end, this would probably show up as uneven rear tyre wear as well.
Can you get someone else to drive the car and you drive behind it on a straight road and see if it looks to be crabbing?

My Touran doesn't drift like this, but the rear camber is probably a bit more than it would be when new, which I put down to softer bushes with the car being a 54 plate, and the front and rear tyres do wear a few mm more on the inside over the whole tyre life.

Your creaking noise when turning, could be the steering swivel bearing at the top of the coil spring, the lower ball joint or the anti roll bar drop link joints, difficult to pinpoint unless the ball joints are worn enough to pick up when levered with a pry bar. replacing the swivel bearing needs the strut dropping out.

When you say "checked all the shocks" did you test them or just visual? You describe a suspension failure so I'd suspect a shock absorber first.