Thanks Rene for the reply, I’m not going to pretend to understand fully the explanation(I will read it again) but do understand most of the important points, and appreciate your time taken..
So I have a nail in the middle of the rear tyre, takes about 5-6 days to register on screen, and then go through re calibration instructions on screen once inflated to turn off the warning lamp..
I’ve discovered front tyre slow pressure loss never ever shows up on screen even if left to deflate to a very low pressure if the car haven’t been used..
So in simple terms the front tyre at 14 psi should be showing up on the the screen like the rear tyre will at a higher pressure but at a loss of about 28psi..