Tires on the Brompton are expensive, you surely want to use them to the max. Experience told me the rear tire last around half as long as the front tire. By swapping the tire between the front and the rear during their life spam, you can really max out the usage on them.
Watch how I explained it at the following video:
00:28 Explaining why the bicycle tires wear off differently between the front and the rear Brompton tires
03:57 Swapping the tires between wheels