Brompton developed their own tyres with a slickish tread, and a casing that can stand over 100psi - they’re good all-round tyres, available in four types:

With or without a puncture-resistant Kevlar band (indicated with a green label)
With or without a Reflex reflective sidewall stripe for extra visibility.

Schwalbe also make a couple of tyres in the right sizes for Brompton - the Marathon, which has a touring bike tread suitable for paths, tracks and slightly rougher terrain, and the Stelvio which is a very light and thin high-pressure racing tyre.