I've just bought a standard RRS MY11 Stormer Edition with the standard 20" stormer wheels on new pirelli tyres and every time I drive over a slightly recessed drain cover or shallow pothole (1-2 inches), the car seems to lurch to the right hand side. It's always when the rear left/nearside wheel goes over it, I'm always in standard driving height and it happens from 30mph+ and is very worrying for a few seconds after - feels a bit like the back end slips out by 10cm but DTC lights etc don't come on to tell me I've lost grip etc. Is this normal? Advice really welcome...

Thats weird. Never heard of this before. Could it be a poorly under inflated tyre? Daft question maybe but does it only happen on one drain or all drains? Nakered hub or wheel bearing?

I'd get my car on a ramp and put both hands on the wheel and give it a push / riggle and see what moves. I'm not Fat. RRS TDV6 HST.

Thank FatJoe - its on all drains, but forgot to mention its only on gentle road bends (left or right)...doesn't occur on straights...

My MY11 does exactly the same and I know all my tyres are fine. It is a weird sensation which I have just learnt to live with.

Thanks Nigel52 - thats re-assuring. As its still under warranty I took it into the garage today and they put it on the ramp and gave it a good looking and as well as taking it for a drive. Everything looks and drives as it should... Apparently its just me getting used to air suspension having just come from a M sport 3 series...

Sounds like a possible shock absorber (air bag) problem.
I expect the wheel is bouncing on the bumps which is causing the vehicle to lurch to one side.
I'm sure if this was normal every RRS would do this, but they don't. The shock absorber should soak up these small bumps & keep the vehicle driving in a straight line. You shouldn't lurch to one side when driving over bumps.
My guess is that the shock absorber isn't absorbing the bumps. RRS TDV6 Overfinch

My money is on wheel alignment being out of spec

As the suspension goes up and down, the toe angles also change. Hitting a bump in the road will extend/compress the suspension, exacerbating the alignment being out

Most places will check your alignment for free, or a small fee, which will put your mind at ease