I don't enjoy Brompton flat repairs on the road, especially in high wind, snow, rain or a deluge of tiny green toads, but there may be times it would be good to be able to. Perhaps practice a few tire on and offs in your warm and cosy home. Sooner or later you will have to replace those tires. By the way, this is why many of us carry a couple of steel tire irons, some no glue patches, a 15mm wrench to remove axle nuts, a pump or CO2 device and either a 10 mm wrench or have converted the cable clamp bolts to Allen wrenches. If your bike has an IGH you will have to learn how to adjust that as well. With Allens in 3, 4, 5 and 6 mm sizes , the 10 mm wrench, a Quick Link on the chain and the above items you can fix or adjust most things on a Brompton. Other goodies, if you don't already have them, are an 8mm Allen, a chain ring nut tool, a crank puller and a bottom bracket tool for drive train issues, and a spoke wrench for a little wheel truing. I think the QR nut for the seat post is 12mm. If you enjoy a good tipple, some like a bottle or two of brew to enhance the tinkering process.