Front track, rear track, offset
I have just discovered that my 2004 156 SW 2.5 V6 (Series 3) on 17" multispoke rims (TOORA model C573) has two ET40.5 offset wheels (its original wheels, part number 60689246, equals 156 & 147) and two ET35 offset wheels (part number 60688033, equals GT, but otherwise identical to the untrained eye). I believe that the front and rear track on the 156 is 151cm and 150cm, and on the GT it is 152cm and 150cm (which by the way means that the GT only has a wider track through the use of the ET35 wheels...), so in both cases the front track is 1cm greater than the rear.
With my ET35 wheels on the back I effectively have the same track (151cm) front and rear, but with the ET35 wheels on the front, I have 152cm front and 150cm rear. The car and the tyres (215/45X17) are otherwise standard, and the tyres don't come near touching anything fitted either way round.
Now here (at last...) is my question? Which way round should I fit them, and why?
Many thanks to all.