Second set of wheels for trails

dUNC
dUNC Posts: 73
edited March 2009 in The workshop
Hi.

I've got a hybrid (Specialized Sirrus) running with 23mm Stelvio Plus tyres for my road commute to work. My missus is wanting a MTB for her birthday so we can start going out, but she's only interested in pootling along paths and trails (and all on the flat :)).

Obviously I'm not going anywhere near those with my totally slick and skinny tyres and with no room for another bike I'm looking at getting a second set of wheels to put more appropriate tyres on to go on jaunts with her.

Even better, it's a chance to upgrade my wheels to something better (thinking like Fulcrum 7s) and use my old rims for the trail.

Now, how do I go about finding out what size tyres my rims will fit, and is there a scientific way to make sure I've got sufficient clearance for some chubbies? I think the bike originally came with 26mm (or maybe even 28mm) Armadillos if that helps.

Thanks in advance.