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2016-08-24 12:34 PM


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Subject: tire question
Hi all,
This is probably a dumb question, but my bike has 700 X 23c tires on it. If I wanted to, can I put 700 X25 tires on it? Meaning, do they fit? Also, any opinions on rolling resistance between the 2? I'm speaking only about width, not brand. I have been reading a lot about how a wider tire has actually been found to have less, not more rolling resistance.
Thoughts?


2016-08-24 1:02 PM
in reply to: Burchib


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Subject: RE: tire question
Excellent question.
A guy I know says tires can be as confusing as pedals.
And sometimes Googling does not provide a readily available and understandable answer, and often leads to far more questions. At least, that's what my friend says.

2016-08-24 1:02 PM
in reply to: 0

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Extreme Veteran
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Chicago, USA
Subject: RE: tire question
Originally posted by Burchib

This is probably a dumb question, but my bike has 700 X 23c tires on it. If I wanted to, can I put 700 X25 tires on it? Meaning, do they fit? Also, any opinions on rolling resistance between the 2? I'm speaking only about width, not brand. I have been reading a lot about how a wider tire has actually been found to have less, not more rolling resistance.
Thoughts?


Not a dumb question. On most (but not all) road bikes, you can usually swap out 23mm tires with 25mm tires.

Yes, you are correct, all other things being equal, slightly wider tires will typically have less rolling resistance than narrower tires. But that is only part of the story. All other things being equal, narrower tires usually have less aero drag (when mounted on rims optimized for that width tire) and aerodynamics usually plays a far greater role in deciding equipment choices than rolling resistance.

My suggestion: for training, go with the widest tires that you can safely get on your bike (heck, I use 53mm wide tires). But for racing, use the fastest and the narrowest tires that your rims are designed for on the front. On the rear, use the same width plus 1-3mm.

(But, note the caveats above, they are important ... )

Greg @ dsw



Edited by DarkSpeedWorks 2016-08-24 1:04 PM
2016-08-24 1:15 PM
in reply to: DarkSpeedWorks


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Subject: RE: tire question
Great info. Thanks!!
2016-08-24 1:50 PM
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Subject: RE: tire question

For training shouldn't be a problem, IF there's no interference from the wider tire with the frame, this is an issue on some frames not designed for wider tires. In general yes wider is faster, but for racing the aero drag impacts should be considered too.  Over on the other site there have been a few good threads lately about tire width Crr, aero drag and the marriage of some data for the two over yaw angles.  One rule mentioned is that tires shouldn't be over 105% the width of the wheel. When possible yaw angles are taken into account aero can go bad pretty quick when tires are too wide for a rim.

Consider FLO Cycling's new carbon clinchers for a sec.  They designed (optimized) the wheel based on the Continental's GP4000 23C tire.  Even then the 45mm, 60mm and 90mm are not the same, the sweet spot for most expected low yaw angles was the 60mm wheel with the GP4k 23c. Bet if they used a "faster" Crr tire such as the GP Super Sonic or new GP Time Trial tire the designs would have been a bit different.

You need to be aware that one brand's 23C tire width may be another brand's 24C or 25C tire. All are not equal.

Also you don't need to pump a 25C tire to the same psi as a 23C tire.  You still get some Crr benefits with lower psi and a better ride quality.  Add in latex tubes to any tire you'll get better Crr and ride quality.



Edited by Donto 2016-08-24 1:51 PM
2016-08-24 2:10 PM
in reply to: Burchib

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Exton, PA
Subject: RE: tire question
Originally posted by Burchib

Hi all,
This is probably a dumb question, but my bike has 700 X 23c tires on it. If I wanted to, can I put 700 X25 tires on it? Meaning, do they fit? Also, any opinions on rolling resistance between the 2? I'm speaking only about width, not brand. I have been reading a lot about how a wider tire has actually been found to have less, not more rolling resistance.
Thoughts?


Yes given the same tire in a three different widths 23, 25, 28 the rolling resistance decreases as you get wider. 25 will fit most road bikes and a lot of tri bike. Make sure you have enough clearance a small rub when out of the saddle is like putting on the brakes.

Now you have the aero vs rolling resistance argument which is better for you? I currently run a 25mm on the back as the frontal area difference is minimal anyway. Then I run a 23 on the front- this is more of a question, do I gain more with the aerodynamic 23mm or with the lower crr of the 25. I think most testing is leaning towards the 23/25 combo.

The 25 in the back also gives a nicer ride, At 170lbs I inflate front to 85psi and back to 85 psi. With 23's front and back I used to pump 85 in the front and 100 in the back.


2016-08-24 4:22 PM
in reply to: Burchib

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Master
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Kailua, Hawaii
Subject: RE: tire question
I just put a 25mm tire on my roadie mainly for the trainer, this gives me better contact with the roller esp when on steeper grades.

Nice road feel as well.

Haven't noticed any negatives.
2016-08-24 5:01 PM
in reply to: Burchib

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Master
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Loughborough, England
Subject: RE: tire question

I am about to purchase some new tires so this thread has been interesting and prompted me to do a bit more research.  I have always used 23c but it seems like 25c is more commonly used due to the lower rolling resistance.

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