Think I might have bought the wrong tubes, it's says 20 x 1 3/8 but it looks like theyre too small for these larger diameter skinny rims and tyres and have to be stretched to fit around the rim. I normally put the tube into the tyre first and then mount the whole lot onto the rim, but the tube is not big enough to into the tyre. Fits fine into a 1.75 tyre.
Anyone got advice on where I can source the correct tubes?