My offside front tyre is peeling tread but the other 3 are in very good condition. Why is this happening? All tyres are inflated correctly as well. Do I need an alignment? Thanks.
If this is only affecting one front wheel there is something seriously wrong somewhere. I would expect a tracking problem to affect both tires.
Possibly you have bent one of the links in the steering mechanism, or something is worn or broken in the suspension on that side of the car, so the wheel is "pointing in the wrong direction" or its camber is wrong and it is only running on the edge of the tire when you are cornering.
Get some specialist advice (i.e. not from your local tire shop which also does wheel alignment!)