Originally Posted by
Jipe
The 20" ETRTO406 wheel doesn't affect the folding,
The limit comes from the space under the front fork.
My current ETRTO406 wheels with 25mm wide rims and Continental Contact Urban 32x406 tires (that are actually 35mm wide on those rims) have a diameter of 478mm in total with tires and just pass with a thin carbon mudguard.
Without mudguard, 3 or 4mm more would be possible, so a total diameter of 484 or 486mm should pass.
For the tire size, it depends of the height of the tire mounted on the rim that depend both of the tire type and rim internal width.
Your 32x406 tyres according to the website is 20x1.25 so of course there is no issue.
However if you use the 42x406 this will cause an issue with the folding as either the rear tyre when folded will hit the frame or you are unable to fold the front tyres.
Just saying that you should stick to 406 tyres with 1.25 diameter just to be safe.