Originally Posted by
WeightySteve
I missed this question.
The Io has a noticeably more narrow rim bed than a standard wheel (including it's mate, the Comete). So putting a 22mm tire on it will mushroom over the sides quite noticeably. Trust me. I've owned the set before and I'm test fit a 22 on there and it's awful. You want a 19mm.
You want a standard 22 or 23mm on the rear to suit the standard sized rim bed.
Here I have a Veloflex Record 19 on the front and Conti Steher 22 on the rear: