Wheel wobble @45 mph

Hi All,This is my first post as I've just bought an '03 1.4i SX for my son.He has the car next week so I've been doing a few jobs,replacing broken trim,service,cam belt etc.
When I collected the car from the dealer I noticed a small amount of wheel wobble at around 45mph.I've had the wheels balanced but it's still there.Tracking has been mentioned,not sure it is that,but just wondered if anybody has had similar problems and what caused it?
Thanks in advance for any replies.

Hi davec,

A wobble at a speed does sound like a wheel balance problem. Maybe one of the weights have come off? Or someone put the spare on?

Its well worth getting the tracking checked, or at least inspect the front tyres for uneven wear periodically, to catch a tyre wearing problem sooner than later.