# 37 mm tires with 45 mm fenders?



## oct3 (Oct 2, 2012)

I'm planning to convert my beater from narrow road tires to sort of Jan Heine's all-road.

He recommends using 28 mm tires with the 45mm fenders they sell. OTOH other manufacturers seem to think 45 mm can fit wider tires than just 28s.

Since I'm not really planning to do gravel on this bike, mostly pavement and some light off-road (grass, dirt roads), any idea whether 37 mm tires are a viable option?


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## headloss (Mar 3, 2013)

Should work fine, in my experience. You just have less margin if the wheel is out of true or picks up some mud while riding. Most 37mm tires are actually narrower than that anyway; take a reading with a caliper rather than trusting what is written on the sidewall.


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## oct3 (Oct 2, 2012)

I'm looking at a nice deal online on a pair of Vittoria Randonneur Hyper, or I would have found out the hard way!

I wanted a light-ish tire that is comfortable, to replicate the Jan Heine experience without the eye-watering prices. These seem to sort of fit the bill at an attractive price point.



headloss said:


> Most 37mm tires are actually narrower than that anyway;


Good to know!


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## Marc (Jan 23, 2005)

Depends on how clean a surface you are riding on.

Generally it is recommended you keep at least 10mm of clearance difference between fender and tire size. Cut it closer that that, and...well...ride though some traction gravel on a highway road or street and you'll learn why.


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## oct3 (Oct 2, 2012)

Yes, and my fenders are of the traditional type, no safety release or anything.

Almost forgot... what's the smallest tube that can be fit in one such tire? ...would 25 be pushing it?


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## No Time Toulouse (Sep 7, 2016)

Traditionally, that 2 digit number meant height above the rim, and the width used to be about the same. So, have you considered height clearance? I know that my road bike with road fenders can accept a 24mm width, but not the height.


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## Kerry Irons (Feb 25, 2002)

oct3 said:


> Almost forgot... what's the smallest tube that can be fit in one such tire? ...would 25 be pushing it?


Tubes are VERY flexible. You could put a standard road tube in a tire that size, no problem. Would it be the best way to go? No. But that's not the question you asked, is it.


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## Jay Strongbow (May 8, 2010)

oct3 said:


> Yes, and my fenders are of the traditional type, no safety release or anything.
> 
> Almost forgot... what's the smallest tube that can be fit in one such tire? ...would 25 be pushing it?


It depends on the quality of the tube. Some blow at the seems pretty easy. Others get comically huge before they blow. 

I use decent quality tubes marked as 19-23mm in 33mm tires no problem and having blown one up outside a tire to test it I can say for sure using it in a 37 mm tire would also be no problem. But I'd tested other 23mm tubes that way and 37mm tire would have been a problem.


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## No Time Toulouse (Sep 7, 2016)

What I've found about using undersized tubes: if the tube is high quality and seamless, no problem. Seams can sometimes fail, and any patch on the tube may come off if stretched too far. Better to use a tube too big, in that case.


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## oct3 (Oct 2, 2012)

No Time Toulouse said:


> So, have you considered height clearance?


I think it's a tight fit: the fender is about 720 mm and the total diameter of the wheel with the new tire should be 703 mm (or less if undersized), so about 8 mm of clearance.



Kerry Irons said:


> Would it be the best way to go? No. But that's not the question you asked, is it.


But nobody likes to flat, right?  Though I happen to have a couple 18-25 tubes (visibly bigger and thicker than 18-23) lying around, I can certainly buy new ones, if necessary.



Jay Strongbow said:


> It depends on the quality of the tube.





No Time Toulouse said:


> Seams can sometimes fail, and any patch on the tube may come off if stretched too far.


Thanks for the input!


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## oct3 (Oct 2, 2012)

My Vittorias finally arrived: they're very nice tires, with a rubber-y bouquet that threw me back to my days as a child, when I walked for the first time into a bike shop.

They're labeled, weirdly, as 37-622, 35x700C (am I missing something here?). What they are for sure, though, is slightly more than 36 mm wide on 17C rims (or 92 mm laid flat).

My heart is breaking while writing this: there's some rub against the left chainstay; either the tire has a slight flaw, or my installation wasn't completely flawless; while the rim tracks true, there's a single spot where the tire will rub, slightly, which makes it all the more maddening, of course.

Truth to be told, there isn't a lot of clearance on the sides of the rear tire, near the BB shell, we're talking a few millimeters, they're _almost_ rideable.

The fenders turned out to be too tight, too. There just seems to be less clearance overall in the rear of the frame, while the front would be OK if not for bolts rubbing against the sidewalls.

Not sure what I'm going to do now: I really wanted to try wide tires and returning these seems such a shame.


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## harryman (Nov 14, 2014)

Well..... can you mod your fenders to gain a little clearance? Try swapping the rear and front and see if you can make it work?

Soma also has a range of incremental sizes if you want to try something a wee bit smaller. Compass too ofc.


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