18 Inch Rear, 19inch Front - MOT

[Dilema1]

BMW 1 Series - One of my rear alloys was cracked, had it welded and it still failed the MOT (apparently new MOT regulations just introduced prohibit welds on wheels). Not sure if that's true but here we are, need it sorted as I need to get through the MOT.

Currently running 19" 9.5J (265/30/) on the rear and 19" 8.5J (235/35) on the front. A new alloy won't be delivered in time before my MOT runs out.

Currently have a random set of 18" rears which are 255/40, think they are 8.5J.

Straight to the point, if I fit these both to the rear while keeping the 19s on the front will they pass the MOT. I know it's not ideal and they will be getting switched back over.