Hi looking for some advise from anyone on here that has had any issues with car vibration while driving on the motorway.
Ok here's the issue so i have just upgraded my alloys from 18" BMW alloys to 19" VC7 alloys with new tyres, I have already had the new wheels balanced and had the tracking/ allinement redone on the car all 100%.
Car drives fine around town and back roads but on the motorway as soon I hit 100kph I can feel a bad vibration in the seat only

nothing in steering wheel, the vibration is there till I hit 120kph then the car is perfect again :smile:, not pulling or anything like that.
Any advise what could be causing this?? Thanks in advance.