If you think about it.. The rims are only 1 inch bigger, and the tyres are 5mm smaller, so your actual increase in size will be 10mm (each side of the central hub) ontop of what mine would be, therefore an increase of 10mm ride-height which means higher centre of gravity ( I know it would be un-noticeable, but just saying the logics )
So IMO ide wack 40mm without a doubt! Wouldn't mind mine 10mm lower....