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I have read a lot and understand some of the points in going with a wider tire than narrower. However I don’t understand a few points.

I can understand that a wider tire has more volume of air and the benefit of running a lower PSI. However, if you go with a lower PSI, aren’t you increasing you chances of a pinch flat? I thought a pinch flat is when the tire compresses (say… courtesy of a pothole) and pinches the tube and you get a hole. So shouldn’t it be best to air the tire to the max recommended to reduce your chances of a pinch flat regardless of how wide your tire is?

My next question is about rolling resistance. I’ve read several comments referring to the study saying that there is less rolling resistance to a wider tire. My issue is if you decrease the pressure of the wider tire by 5 – 10 PSI, as many have said they have done on this forum for comfort, are you not increasing the contact patch even more than just the wider tire and thereby increasing rolling resistance even more?

Lastly, what about the aero drag increasing from a wider tire? And not just from the front. The trailing end of the tire, which is now 2 – 3 mm wider than the thinner tire you took off. It seems to me that the wind has to break around the rim then even more drag as it moves around the now even wider tire.

Oh, and what about the added weight of a wider and heavier tire? That can't speed you up.

Other than comfort, with lower PSI, are the benefits of wider tires really better?

What am I missing?

Shuffleman

I always road 23's but read a lot of the geek speak and thought that I would try the 25's when it was time for new tires. I honestly can't say that I notice any difference in comfort or loss of speed. It would be more than nominal if it were a loss in speed. I place the same as always in group rides with the same effort. Honestly there are always opinions on this but to me it feels like people trying to sell you on whichever they have or use. I guess that goes for bike brands as well

Elvo

nastystang

The idea with the lower pressure is the tire conforms to the abnormalities in the road as with more pressure you would just bounce around over them. I like to ride a high TPI tire that also does this. The idea is to decrease the pressure to a point the pinch flats are still a non issue and rolling resistance is still low. I weigh 140 and ride 90 front and 95 rear with Vittoria Corsa Evo's. Personally I ride a 23 but most prefer the 25. As far as drag from tire width I doubt it's even percievable.

JerrySTL

My best distances in a few 12 and 24 hours races were after I switched from 700x23s to 700x25s and lowered the tire pressures by 20 psi. These races were on somewhat rough chip and tar roads and I certainly wasn't beat up as badly.

Of course I just might have been in better shape or the weather was better; however, I still give a lot of credit to bigger tires at lower pressures.

As far as pinch flats, I haven't had one since going to the 700x25s at 90 to 100 psi. Seems to be less punctures also.

StanSeven

The aero piece isn't mentioned much. While wider generally has less rolling resistance, around 30% gets added back into the reduction from aero drag

Drew Eckhardt 

Yes, although the larger tire has to deflect farther before there's a problem so you can run lower pressure for the same risk of pinch flat.

I don't remember the last time I pinch flatted and might have avoided it with more pressure, although I regularly benefit from increased comfort, riding over obstacles like railroad tracks over a dozen times a week and bad pavement many times each year.

Wider tires are faster by enough of a margin you can have both lower pressure and lower rolling resistance.

Tour magazine only measured a 1W difference dropping a 28mm Continental GP4000SII from 7.5 bar (109 psi) to 5.5 bar (80 psi) so there's a lot of latitude.

In Continental's measurements a 25mm GP4000SII has lower rolling resistance at 87 psi than a 23mm one at 109 psi.



It depends on how the tire interacts with the rim.

Speed differences up the steepest hills are proportional to the total difference.

My bike and I total 72kg, so the 20g/pair difference (225 vs 215g each) between 23 and 25mm GP4000SII tires slows me down at most 0.03% or 1 second an hour.

That's not significant before you offset it with the rolling resistance decrease and how the athlete performs with lower fatigue.

Heavier riders would be even less affected, and the difference on flat ground would not be measurable.

hairnet

Overthinking. Do you like bigger tires? Great. No? oh well.

knobster

I'd love to see some actual references for this statement. I've read on Bicycle Quarterly that aero drag is a non factor at the speeds that bicycles typically go.

knobster

OP, I don't think you'll notice enough difference going to a size 25 than what you'd want, but most "racing" bicycles can't accept tires larger than 25 so it's really a moot point.

rms13

There has been lots of discussion in my club about this recently and someone posted this informative article:


The Tire Pressure Revolution, by Jan Heine | Road Bike Rider

The key is you also need wider rims not just wider tires to see true benefits. Personally, 700x23s at 120 psi have been working just fine for me riding in an urban area for about 5 years now and I see no reason to change. I have had wider rims and 25, 28 and 32 tires on different bikes and I'm fine sticking with 23 on my road bikes

StanSeven

I'm just using my phone now. Check aero weenies.com for some data. There's also a July 2012 Velonews test of aero wheels. They used tires from one tire manufacturer at various widths on all wheels tested. The most dramatic variation was 97.

None of it is much but neither is the resistance between 23 and 25 tires. So 30% of a little is very little. That's probablt what Bicycling Quarterly was referring to.

kingfishr

Can you please provide your evidence for this? I am using my my 7 year old fulcrum 3s and Mavic Cosmic Carbones and running Continenatal 28mm tires at 80psi back and 70psi front and it's so much more comfortable with no difference in my performance.

Long Tom

Pinch flats = non issue. I'm a Clyde (barely)... I never get one. Ever.

Wider tires = smoother ride

iDK about aero drag. Seems that a wider tire has to be a bit heavier, so there's a tad more rotational weight. But personally, 25's or narrow 28's (grrr!) are still worth it.

tomato coupe

Let's see if I've got this right:

(1) If you drop the pressure of your 28mm tires from 109psi to 87psi the increased rolling resistance will cost you about 1 watt of power. The implication is that this is not significant.

(2) A 25mm tire at 87psi has less rolling resistance than a 23mm tire at 109psi. The difference, however, is about 10 times smaller than what was dismissed as insignificant in part (1). In other words, the higher rolling resistance of the 23mm tire at 109psi will cost you about 0.1 watt.

Conclusion: Wider tires may be more comfortable, but any claim of lower rolling resistance is kind of silly because it doesn't amount to much.

Blue Belly

I worry about propaganda when I comes to the wide tire issue. The contact picture, specifically, seems a little funny. My thoughts on the issue are dependent on what, how & where you ride. There are far too many variables to say any 1 tire is better for all riding environments & riders...

tomato coupe

I think Continental does everyone a disservice publishing a diagram with such exaggerated contact patches. The fact is, both "narrow" and "wide" tires will have long, narrow contact patches. A circular contact patch would require the tire to have a cross-sectional diameter that is as large as the diameter of the wheel, i.e. it would look like a beach ball.

Carbonfiberboy 

A good illustration of the purposely stupid at work. One inflates tires of differing width so that the contact patch on both is the same length. One never inflates a wider tire to the same pressure as a narrower. And duh, if the pressures are equal, the contact patches will also be of equal area. Thus on smooth roads, narrow tires at high pressure are always faster than the same casing in a wide tire at a lower pressure. Thus TT riders run 23s or narrower at 140 lbs. if the course is smooth. There's a reason that Vredestein Tricomps have a max pressure of 11 bar. Unfortunately they always get their Crr tested at 7 bar where they are nasty mushy.

There are good reasons for running wider, softer tires, but the above is not it. Interested BFers might enjoy commenting on the marketing reasons for Conti publishing such utter hogwash.

Doge

My son, who races, uses both. The wider offer more confidence in rougher roads. The preferred are 25mm, but he trains on 23mm.

Lazyass

That's not really correct. We're talking about a 2mm difference in size. It's not the same as trying to put a 190 rear sportbike tire on a 5.5 inch wheel designed for a 180.

Wilfred Laurier

I believe the difference in rolling resistance (energy hysteresis) is really negligible when riding at what most people consider a decent cruising speed or above. By far the biggest drag that a rider has to overcome on flat ground is the aerodynamic resistance of the rider and bike (including wheels). When climbing a steep hill the primary resistance is the weight of the rider and bike, and this is still much higher than rolling resistance. Narrow tires can reduce the aerodynamic resistance and the weight, but require higher pressures to prevent flats, and the higher pressure results in a less comfortable ride, and is therefore used usually when speed is the most important result.

wphamilton

Increasing the size or shape of the contact with the ground does not increase rolling resistance, not directly anyway. The resistance, or most of it, is from bending the casing. The contact patch relates to how sharply the casing is deformed, and where, but that also depends on a few other factors. In my opinion, when tire manufacturers come out with their analysis based only on the shape of a contact patch, proceeding as if that proves something, they are just blowing smoke.

For a long time I've mulled over one observation, which doesn't line up with these studies and analysis. That is, when you get to the lower end tires, those with thick or hard rubber compounds designed for durability period, and with puncture layers, it doesn't hold true. Those tires, wider is slower and when you drop pressure to a certain point, you will know it. It's the material, and the construction - the tires just do not like to bend more than a certain amount, and that means drag. So, when we talk about lower pressure and certain tire widths reducing drag, by any amount, I think it's important to remember that it's valid within the context of a certain tier of quality and specific types of tires, and shouldn't be generalized to just any tire we might order from Nashbar or Amazon.

Blue Belly

I'm going to say it. Until it's proven to me, my experience tells me that more contact surface & tire weight are going to provide more resistance. Therefore, making you slower. My examples are extreme, & I understand comfort, over a long ride. However, I built a cyclocross bike, a few years ago. I fit it with 34cm tires(sewups, if that makes a difference to you). I then downsized to 32mm. Same tire brand/model. On a road or solid surface, the 32mm tire was so much easier to spin up & maintain. I realize these aren't a smooth tire but, they aren't that heavy either. On a climb, having that extra weight & tire contact surface, of the 34mm created more work to maintain a rythm. The only thing a wider tire did was help me stay upright on loose soil. Call me silly but, some of this translates to a 20/23 to 25/28mm jump? I've ridden rough riding aluminum & even steel bikes that certainly tax the body, after a day of hard climbing. So, I'm well aware of comfort being an issue. But I've also ridden light 20mm tires after a competitive 23cm tire & felt the ease at which they spin up & roll with a small contact to the ground. Aero dynamics honestly don't impress me too much, in these smaller sizes. But, it must make some difference? I'd be much more concerned with rolling weight & how smooth the compound of the tire reacts with the surface of the Tarmac. The same things, coincidentally, that make a great wheel! So, why would you add weight or unnecessary width to a tire/wheel combination? im still not convinced.

Sy Reene

Found through a link someone posted further up in this thread.. is this the type of data you're looking for?
https://janheine.wordpress.com/2015/...a-and-details/

Some excerpted copy from the other article that was posted in a post above:
"No matter which route you took, the science of the day predicted that your wider tire would be slower. It was a Catch-22, and for the best performance, you stuck with narrow tires, where you could have a supple casing and high pressure at the same time.

You can see where this is heading. If lower pressures don’t make tires slower, then you can create wide tires with supple casings. You run them at lower pressures, and you don’t give up any performance on smooth roads. On rough roads, you actually gain speed, because the tire (and you) bounce less. And on all roads, you are more comfortable. Instead of a Catch-22, you have a win-win-win situation.

It took a while for this research to become accepted, but once the professional cycling teams started testing tires with power meters on the road, they found that the wider tires, run at lower pressures, were as fast, or faster, than the narrower tires they had been running. Add to that the better cornering grip – more rubber on the road, less bouncing that can break traction – and it didn’t take long for the pros to go from 23 to 25 mm tires.

23 to 25 mm may not sound like much – less than 10% wider. But when you look at the air volume – the area of a circle goes up with the square of the radius – you get 18% more air volume. That is significant.

On smooth roads, 25s are about as fast you get – our research indicates that 28s and 32s aren’t slower, but neither are they any faster (that includes air resistance at speeds of about 18 mph). That means that if your bike can handle wider tires, you can get more comfort and better cornering with wider tires, without losing any speed."

StanSeven

I'm not questioning the conclusion or the point that 25s are fast but this statement is ridiculous. How can anyone with a power meter on the road prove one tire is faster? Think about all the variables too