Originally Posted by
12boy
Brompton wheels are 349 but there is also a 16 inch 305 rim. Those wheels will fit with larger tires and wind up about the same diameter as the 349s with 37 mm tires.
You should mention that apart from the need to respoke the wheels with smaller rims you also run into issues with the brakes - the arm length with the stock brakes is not long enough. There are solutions to that via adaptors or other brakes but that is extra work and investment. Also I would not be sure if 305 Big Apples fit an unmodified frame. The Bromptons with 305-Big Apple that i know of had at least a modified rear frame, but the modification was due to the hubs, so maybe it would fit with a stock frame and maybe not.