Could be worth checking if the tyre weights haven't come off causing the balance to be out. Have you had 4 wheel lazer alignment after fitting as that could be another possibility.
Had lazer alignment done, I know there are new weights on the passenger side but not sure about the drivers side, however there is nothing on there now (that's the side I think it's coming from, although that could be because it's closest).
Would an MOT pick something like that up? Got mine in 3 weeks...