Ok.. I'm no expert, but if my calculations are right.. then the closest in rounded off metric would be ID: 2.5mm OD:4.5mm.
I found a supplier in sweden who specialize in tubing and such.. but they only showed ID and wall thickness.. and when I try to figure out the OD by the wall thickness I should double the lenght of the wall thickness, right?
Here below are three different thickness with the same ID.. which one should I go for? If I'm right, it,s the first, right?

*Ø 2,50 mm *1,00 mm *25m
*Ø 2,50 mm *1,50 mm *25m
*Ø 2,50 mm *2,00 mm *25m