Tracking question

Hi all, my first post here :-) and I start with a question:

My front tyres are a little worn on the inside and, suspecting I needed to get the tracking looked at, booked my car in at a nationally - recognised company.
When I arrived, the guy on reception marched out to my car and said I'd need two new tyres before they could do the tracking.

I thought the tracking was carried out on the suspension and affected the direction of the wheels (hence the alternative term 'wheel alignment) - surely this has nothing to do with the tyres.
If anyone could confirm or otherwise that would be great.

Many thanks,

Tom F.