I just returned from a trip. Since the wheels were already off the bike, I decided to fit a pair of Stelvios to my Birdy (355 rims). I was told that I should use 1 X 16" tubes (349s). But the tube doesn't seem to fit perfectly in there. (I can't tuck it all into the tire.) I though I had it in, but had a blow out, with the lip of the tire coming off the rim. There is also a tiny bit of rubber shredded off the bottom of the wire, but it doesn't look like it is interfering too much with the seal against the lip of the rim. Any suggestions?