Any question answered...

Why does my rear tyre keep deflating over night...

I have put three new tubes in, new rim tape, checked the inside of the tyre for sharp bits, checked spokes for sharp bits, Im pretty sure its not a pinch puncture, having changed 100's of tyres and not had them before...

Its a slow deflate always overnight.

Any ideas?

So, the tubes you are removing- they have a hole in them?
Is it always in the same place?

How old is the tyre?