I ordered my new Brompton with Schwalbe Stelvio tyres. I noticed slight bulges / kinks in both tyres with the rear being worse than the front. Over the weeks they steadily got worse to the point of making the bike shimmy and unstable while going fast downhill.
I ordered a pair of 32-349 Schwalbe Kojaks and spare inner tubes. Upon striping out the original tubes I noted an uneven profile so the problem could be partially tubes and tyres.
You might be able to see the twist / bulge in the front tyre in this photo (there is the bulge in the centre and you might see the twist by following the line of the rim, top edge in the foreground).
I fitted the Kojaks without any trouble and took the bike for a ride..... what an improvement, much better. I’m really pleased. The real test will be the fast downhill ride to the railway station tomorrow evening.