the track is the distance between the centres of the tyres. Now, if we assume that the wheels have a 15mm offset, which is probably about right, then the length of the axle comes out at 52 inched + 2*15mm: 53.25 inches or so.
This is because a positive offset of 15 mm means that the mounting face of the wheel is OFFSET 15 mm towards the outside ("street side"
of
the wheel. Cortina track is about 56 inches IIRC.
Hope this helps.
Ed.