Anyone running 40mm tires on 25 internal rims? What do they actually measure?

[Tommasini53]

40mm Schwalbe G-one Speed; Campy Levante wheels (25mm) measure out at 40.5mm.

[Will_Elder]

Originally Posted by makoti

Perfect.
How do you like those tires? Anything to compare them to? My only gravel tire experience is the GK's SS+.

Sorry this is my first gravel bike, so nothing to compare to. First spin yesterday was a lot of fun!

[rice rocket]

Originally Posted by makoti

Thank you.
Surprised that the 40s were actually less

I think a lot of people give out numbers right after mounting (because who measures it again after the initial fitting), but tires stretch a little after some use.

Does the Terra Speed stretch more than other tires due to their lighter construction? Perhaps? Mine measure 40 after two years, I don't use them much as they are my race rubber.