Thanks for the interest.
The values for Front/ Side / Rear (Hit, Critical, Save) are based on several factors: actual armour thickness, size, sloped armour, running gear etc. etc. And yes, most AFV had the thickest armour in the front and the weakest in the rear.
But if a real world tank has better armour protection in the rear (compared to the side) it will be reflected in the gaming values.
As far as the Panzer I F is concerned, yes it had such a thick armour, it was a strange little vehicle, only armed with MGs but armoured like a big one! (Search the web about this little bugger, very interesting!).
So no runes or other magical stuff, just different real world stats!