I'm not too sure about your tire measurements on the other side of the pond, but Im thinking that your new tires are taller than the stock ones? When I went from stock to 265/75/16's I noticed a vast difference between ride qualities Like you mention. I pretty much am used to using two hands except momentarily or straight smooth roads. On rough surfaces it really is a fight, but manageable. It seems to handle ok on hard left or right turns, but has a lot of play between the exremes. I dont think anything is wrong- but who knows maybe something is bummed up under your truck somewhere. Good luck