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

[makoti]

As it says, wondering if anyone is running this. Specifically, I'm looking at the GravelKing SS+.
Thinking about doing a set of Levante, but my rear triangle is limited to ~43mm. Want to see if they would "likely fit or should I stick with the 38s I have now.

[nmrt]

Running 40 mm tires (Conti Terra Speed) on 24 mm rims. They measure 39 mm.
On the same rims, I also ran 42 mm tires (Ultradynamico Cava JFF). They measured 42 mm.

[Will_Elder]

I am also interested in this topic!

I have an Open Up being built tomorrow with a Levante wheelset, Pirelli Cinturato Gravel H tyres in 40 mm going on.

The Up has clearance for 40 mm tires so will see if they fit and report back.

[makoti]

Originally Posted by Will_Elder

I am also interested in this topic!

I have an Open Up being built tomorrow with a Levante wheelset, Pirelli Cinturato Gravel H tyres in 40 mm going on.

The Up has clearance for 40 mm tires so will see if they fit and report back.

Please do!

[makoti]

Originally Posted by nmrt

Running 40 mm tires (Conti Terra Speed) on 24 mm rims. They measure 39 mm.
On the same rims, I also ran 42 mm tires (Ultradynamico Cava JFF). They measured 42 mm.

Thank you.
Surprised that the 40s were actually less

[Jdm]

My 40mm Terra Speed tires on 25mm roval rims surprisingly measured 40mm

[fa63]

Gravel King SS+ is available in 700x38c or 700x43c:

https://www.panaracerusa.com/products/gravelkingss7b

Even though the ETRTO designation for that 38c tire is 40-622, the Bicycle Rolling Resistance's measurements on the SS model had the 38c tires measuring at an actual 35.9mm width mounted on a rim with 18mm inner width. As a general rule of thumb, each 2 to 3 mm increase in rim width is roughly a 1 mm increase in tire width, so on a 25mm inner width rim, that 38c tire should theoretically measure pretty close to 38 mm.

[makoti]

Originally Posted by fa63

Gravel King SS+ is available in 700x38c or 700x43c:

https://www.panaracerusa.com/products/gravelkingss7b

Even though the ETRTO designation for that 38c tire is 40-622, the Bicycle Rolling Resistance's measurements on the SS model had the 38c tires measuring at an actual 35.9mm width mounted on a rim with 18mm inner width. As a general rule of thumb, each 2 to 3 mm increase in rim width is roughly a 1 mm increase in tire width, so on a 25mm inner width rim, that 38c tire should theoretically measure pretty close to 38 mm.

That is so last year. ;-)
https://www.panaracerusa.com/collect...ng-gravel-tire

[fa63]

Aha, good to know

BRR has the 2024 model year Gravel King R 700x40c measuring at 38.8 mm on a 18mm inner width rim, for what it is worth.

Originally Posted by makoti

That is so last year. ;-)
https://www.panaracerusa.com/collect...ng-gravel-tire

[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.

[phishrabbi]

Originally Posted by nmrt

Running 40 mm tires (Conti Terra Speed) on 24 mm rims. They measure 39 mm.
On the same rims, I also ran 42 mm tires (Ultradynamico Cava JFF). They measured 42 mm.

The terra speed 40mm are notoriously narrow, and run about as wide as a 38mm gravelking (or RH) slick.

[marciero]

Originally Posted by nmrt

Running 40 mm tires (Conti Terra Speed) on 24 mm rims. They measure 39 mm.
On the same rims, I also ran 42 mm tires (Ultradynamico Cava JFF). They measured 42 mm.

My UD Cava Race run 44mm on i25 rims. They list the size as "42??". The increased width might be down to the casing difference. @Will Elder - they fit fine on my Open U.P.

[Nomadmax]

Gravel King SKs in 43mm measure 43mm on my Levante wheels at 40psi rear, 35psi front.

[jasflyfisher]

For me, previous generations GK SS 700x38 mm tires measure out to 40.4 mm on 25 ID rims @ 37-ish PSI. Probably about 8-900 miles on the tires.

[Will_Elder]

I have just been for my first spin and Pirelli Cinturato Gravel H tyres in 40 mm measure a touch over 41 mm on Levante (25 mm internal)