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TIRES Schwalbe Lugano 700x25c
Any tire marked with 700x25c or 25-622 will fit
700x25c says that the nominal diameter is 700mm and the thickness is 25mm
25-622 says that it will fit in a rim with a "Bead Seat Diameter (BSD)" of 622mm and thickness 25mm. The bead seat is the groove on the inside of the rim that the tire fits into to stop it popping out, probably a more important value than overall size.
The new tire could be larger or smaller than the 25mm. The limit depends in the internal width of the rim. For example if your rim is 15mm wide internally, you can fit tires from 23 to 32 on with confidence. Outside this, the confidence level drops the further you go.
You should also consider the clearance your frame has for fitting wider tires. I an mot familiar with that bike so can't advise, but you could measure the width of the forks, seat stays and chain stays at the point where the tire passes. The brakes you have could also limit the tire size.
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Sheldon Brown