OK, so bit of an update. Apart from the bumping / clunking /whatever issue, there was a bit of that waaa.... waaa... waaa... waaa... sound that varies with wheel speed coming from the front. It was more noticeable at low speed and when slowing to a stop, and I was picking probably a wheel bearing on the way out. But reading a lot of posts on many different forums indicated that sometimes a tyre can cause this kind of noise.
So off came the front wheels (Goodyear 235/40-18XL assymetric tyres 50% worn) and on went the front wheels from my new set (Neuton 225/40-18 directional tyres 20% worn). Went for a drive and dang me... not only did the waaa... waaa... noise disappear, but the tyre thumping over road surface irregularities was also considerably reduced !!! The ride and noise level is now pretty much in line with what I expected from a BMW
I have never never owned a car that used anything lower that 55-series tyres, so had no experience with 35 and 40 series tyres to guide me. With such short sidewalls the tyres cannot absorb much bump energy which means that the suspension does more work. The upside is much crisper handling and I'm all for that.
Looking at the Goodyear tyres, they are XL rated which I gather means that they are stiffer to handle Xtra Load. They are also assymetric AND directional, which as I understand it means that they come with 1 x RH and 1 x LH tyre to make an axle pair. However, it looks like the tyre shop mounted two identical tyres which means that one was rotating in the wrong direction. I think the combination of a heavier tyre and greater wear caused the thumping and the incorrect mounting and/or tread wear contributed the extra noise.
Cheers... jondee86
"The only reason I make mistakes is so that I can learn from them...".