Vibration that comes in around 50mph, peaks at 60-65, then fades is a textbook wheel balance issue — usually a thrown wheel weight or a buckled alloy after a pothole. If it shakes through the seat as well as the wheel, suspect a rear wheel or a worn hub bearing.
Common one this — especially in Scotland after a winter of frost-heaved tarmac and surprise potholes.
Could it be tracking or alignment? — Bad alignment makes the steering pull or eats tyres unevenly — it doesn't usually cause a vibration on its own. If you've got a vibration AND uneven tyre wear, get both done.
Why does the shake only happen between 55 and 65 mph? — That's the classic balance-issue rev range — the imbalance resonates with the suspension at that speed. Below 50 it's too slow to feel; above 70 the wheel spins past the resonant frequency. Almost diagnostic.
Is it safe to drive on the motorway with it shaking? — Short answer: short journey at moderate speed, fine. Long motorway runs, no — vibration kills wheel bearings, tyres and your steering rack. Sort it within a couple of weeks.
Bob's Mechanical Repairs — independent family-run garage in Birnam, Dunkeld, Perthshire. Call 01350 727 276 or email [email protected].