somebikeguy 

I'm trying to maximize width on an older frame. I have measured clearance just over 35mm so tried some 35mm Gravelking SS+ but found them to be actually a hair over 36mm. Their side tread rubs the stays. Does anyone have a nominal 35mm tire that measures 35mm or less, inflated? I am running tubeless, 20mm ID rims (Pacenti Forza).

Failing that... I really don't want to dip down to 32mm which is the next size down in gravelkings. Any experience with 33, 34's ?

I can't do 650b because this is a canti brake bike and I will be using some super duper Paul canti's I have on hand.

t2p

our 35mm GK SS also measured around 36-37 mm installed ...

of course - the 32mm GK SS measured smaller than 32mm ...

Continental 35mm GP Urban measured around 31mm (on the same rims the 35mm GK SS measured 36-37 mm) ...

Continental Terra Speed 35mm measure around 33-34 mm ... despite the shallow knobs they roll relatively well - possibly and probably as fast or faster than a GK SS

somebikeguy 

I have Terraspeed 35's on my 650b bike and they're ~35.5mm. For sure a hair less than the ~36mm Gravelking SS+ but they're not cheap and I think I'd feel pretty dumb buying one and having it also rub...

t2p

I have 700 x 40 Terra Speeds on one bike - 650b x 40 Terra Speeds on another bike - on both bikes the tires measure around 38-39mm ... just a bit under listed width ...

on an old school road bike 25mm GP5K’s measure close to 23mm ...

the worst offender was the 35mm GP Urban at around 31mm ... I installed one and quickly removed it ...

the only recent Conti tires I’ve measured at the listed width are 32mm GP4S @ 32mm

chaadster

if you have just over 35mm of clearance, it’s going to be very hard to find a 35mm indicated tire to fit. Between the wide 20mm IW rim— assuming you meant width and not ID or diameter— tire pressure and casing stretch over time, you probably just don’t have the space and will have to size down to a nominal 32mm.

Because of all the variables and variances you might find a 35 that fits, but unless you’re extremely luckly, it’s going to be expesive and time consuming doing fit by trial-and-error.

shoota 

Sounds like a 33mm Terreno Dry would fit, if you can find them.

tFUnK

It's difficult to recommend a specific tire due to the fact that manufacturers may have made changes in response to wider rims (eg, Conti GP4Ks used to measure out wider but recent models are substantially narrower).

​​​​​​But iirc, Conti Cyclocross Speed tires used to come in a 35mm width and I think they measure out just under that on a 17mm IW rim.

The other thing to consider is to look for CX tires that are marked as 33mm, and hope that they measure out slightly wider with a wider rim. I don't have a specific recommendation from the top of my head but I'll dig around in the garage this evening a bit to see if I have some examples to share.

msu2001la

There are some 33mm CX tires with minimal tread:
Challenge Dune or Chicane
Vittoria Terreno Dry
Donnely LAX

Pretty sure you can get any of those in tubeless clinchers - they're all pretty nice tires. I have used different variants from all 3 brands for CX racing, but have never measured the actual widths.

If you have measured clear width on your frame of 35mm, it seems like even a 33mm (leaving just 1mm of clear space on each side) would still be too tight.

somebikeguy 

Much appreciated! I will give a 33mm a try. My measured clearance @ 35mm tall tire is ~35.75 so @33mm tall it ought to be more. I believe 33mm will fit.

tFUnK

A thought just occurred to me that some of the CX tires may not be tubeless compatible.

Polaris OBark

Rene Herse 35mm: https://www.renehersecycles.com/shop...-bon-jon-pass/

Rene Herse 32mm: https://www.renehersecycles.com/shop...stampede-pass/

I run the 38mm Barlow Pass tires, which are true to size. The others are reported to be as well. In general, add 1mm if tubeless, just to be safe.

somebikeguy 

The RH 32 is not Tubeless compatible but the Chicane, Donneley and Vittoria are listed as such. I haven't used any and would need to dig further or ask you all for reviews to pick between them. Or I could go for the Donnelly cuz it looks good and I like the price

https://us.challengetires.com/shop/p.../chicane/55153
https://cambriabike.com/products/don...a3936f67d5223a
https://www.jensonusa.com/Vittoria-T...7b9e91af1b49b2

somebikeguy 

And btw the frame in question is a first gen swiss cross (in case anyone has direct experience). The crazy thing is the fork was designed for a 40mm tire and in fact my 43mm gravelkings juust clear.

tFUnK

Ah yes I did see that build thread. Like you, I've found that the rear clearance is the one that's typically lacking. Reminds me of the MTB days when we used to run slightly wider fronts for better traction. I'm contemplating going with a 38mm in the back, 44mm up front. I might try to hunt down a 29x2.0 or 1.95" just to see if it clears the front. The issue is I'm used to f/r specific tread tires for MTB and gravel tires don't come like that, it seems.

somebikeguy 

On my later model Swiss Cross I fit 43 at the front and 38 at the rear. I will see how bad of an idea it is to keep that 43 at the front, if nothing else I can use my old 38 panaracer and then go to the 33 at the back. Not quite as rugged but the old frame is just too damn cool.

chaadster

There is no such thing as “true to size,” as it depends on the internal width of the rim.

grolby

Back when this frame was built, 28 or 30 mm tubular cyclocross tires would’ve been pretty typical, with maybe up to 32 being available. Your measured clearance reflects that. It’s a 25 year-old cyclocross racing bike, CX bikes were very niche at the time. It’s not really going to turn into a gravel bike. I know the fork clearance makes it seem kind of absurd that the clearance in the back is so tight, but the fork is probably that wide to accommodate cantilever geometry and ensure the brakes are properly spaced from the rim. Fitting a big tire wouldn’t have been the intent and it won’t handle as the builder intended with one anyway. Wide 700C tires were for cheap hybrids and touring bikes at that time. I think 32 is probably the limit, here.

Polaris OBark

Next thing you know, you will enlighten us by proclaiming the Tooth Fairy doesn't exist, either.

chaadster

Oh? Are you planning to make a silly comment about the Tooth Fairy being real, too? In which case, yeah, I will.