There is an argument for using a slightly wider (than standard) tyre on the front, and standard on the rear. More tread, possibly better grip, better feel, perhaps. We're so used to bikes having a symmetry in sizes front and rear, for road use at least, that it seems strange at first acquaintance. Off road bikes regularly use wider on the front. My definitely non standard Linear recumbent has a wider tyre than standard on the front than the rear, and it works. Of course we're not all downhill racers but the principle still applies. A by product of doing this, at least with a Brompton, is that you are still more likely to be able to use mudguards.