Rob_benton said:
I had this a few weeks ago and it was a seized passenger front calliper. Same issue at 40mph.
Have you felt if one alloy is hotter than the other after a drive ?
I had this too, at first it was an intermittant problem and I checked the temp of the wheels but I couldn't feel any difference. Eventually it got worse and I then could tell the near side front alloy was hot and booked it in to have the calliper refurbished and this sorted it. With the calliper problem it was steering wheel wobble that you couldn't drive through like an unbalanced wheel, does your wobble improve at different speeds? I hope you get it sorted soon as it does affect the driving enjoyment.