Gillyg, Thanks that makes it seem back to front..... which is why a picture paints......
I had it my head that the 255 was the one to go for as it was bigger, and now i know why the 235 are more popular so thanks again, Just to add even more confusion, i've swayed from the GG AT3 towards the Pirelli Scorpion All Terrain Plus which comes in 255 x 60 x 18, Which may well be too much for the arches, it also puts the clocks out 10% so that's not great...... Might have to go down to 17's ?
I'll have another play on the configurator,