Right , REALLY needing some ideas from the collective masses on this one as I'm not now convinced its the tyres....
Just done 1300 miles in a round trip to the Le Mans Classic and the rumble is still there no better and no worse full list of symptoms are...
1) Heavy rumbling noise related to road speed, kicks in about 35 to 40 and quietens down around 85 - 90 (so thats the auto route speed we chose for the run back through France)
2) Gets worse with the car loaded.
3) Doesn't change with road surface (hence why I dont think it is road surface / tyre related)
4) going over bumps that take the load off the tyre / suspension makes the rumble quieten down.
5) Changed rear wheel bearings already and front upper arms !!
Help and ideas greatly appreciated as this has taken the shine off a brilliant long weekend with the car which performed faultlessly and still looked good even in esteemed company.
Another note is I'm going to get rid of the 18's I dont think they suit the GT nature of the car especially on long A road runs....