QUESTION: What size tire should I be riding on my road bike? Ten years ago, a 25mm tire was considered really wide, but now everyone is saying that 28mm is the standard and you can go even wider than that. My frame will accept up to a 32mm tire. I don’t race, but I do like to do fast group rides, so I want to keep up. —Willie R.
RBR’S STAN PURDUM REPLIES: What you’re hearing about wider sizes is correct. In fact, most riders in the Tour de France now run 28mm tires.
Jan Heine, the publisher of Bicycle Quarterly, is responsible for some of the testing that led to the move away from skinny tires, and he says he doesn’t even consider anything narrower than 32mm, and he rides 42mm tires on paved roads. He cites studies showing that for road riding, 21mm and 23mm tires are the slowest. The next sizes up are all faster, with no significant speed difference between them up to 53mm. (See his book, The All-Road Bike Revolution, Bicycle Quarterly Press, 2020, page 139.)
But there’s an important caveat. According to Heine, the fastest tires, regardless of size, have supple casings, which are made with fine rather than coarse threads and are woven with a loose enough weave that the casing is not stiff. Heine says that when it comes to speed, tire width and tread compound are secondary to supple casings. (same book, pages 137-138.)
Translating all of this to the real world, however, doesn’t have to be complicated. For one measure, you could simply ask your fast-riding friends what tires they rely on — including brand, model and width. If you find that several of them prefer one particular tire, try that.
However, if you’re already keeping up with your fast club-ride friends on tires that are narrower than what they are running, why change? At least, wait until you’re ready for new tires and then bump up a size or two.
Of course, there are other advantages to wider tires. They don’t fall as easily into road cracks. They negotiate broken pavement better and, because they run with lower pressures, they provide a more comfortable ride. They also provide better handling for those times when you come across an unexpected gravel stretch of road.
Stan Purdum has ridden several long-distance bike trips, including an across-America ride recounted in his book Roll Around Heaven All Day, and a trek on U.S. 62, from Niagara Falls, New York, to El Paso, Texas, the subject of his book Playing in Traffic. Stan, a freelance writer and editor, lives in Ohio. See more at www.StanPurdum.com.
I’ve got a few newer bikes in my Service Course, disc brakes, wider tires…all the ‘modern” stuff. But my favorite road ride is my 2003 Litespeed Tuscany. Recently upgraded the drivetrain to 11 speed with slightly wider wheels. Found that only up to 25c tires is the best I can go. The slightly wider rims barely clears the chainstay and seat tube. I realize that tire size slightly varies by manufacturer, even product line. I’ve go no intention to retire the Tuscany to trainer duty. It’s still my forever ride.
What about the rim those wide tires will go onto. All my rim brake wheels will accept up to 28mm. Then we enter in the wider tires being tubeless and not made for Hooked wheels another consideration. I can say this I’ve switched out 25mm Continentals to 28mm Vittitorias and the ride difference was a pleasant surprise with no additional rolling resistance.
If the rims can support 28mm, try the continental GP5000 TLR or the Pirelli PZero race TLR. Both can be run with tubes and will give great grip and a nice ride feel.
I run tubeless 700x25c Conti’s at 60-70 psi which makes them measure 700x27c. 25c is lighter than larger tires, it takes fewer watts to rotate these moving parts. Good solution for the older frame that can’t handle larger tires.
I agree with all the mention advantages of wider tires. For the pros, wider tires and lower pressure are definitely an advantage speed and comfort wise.
For the average rider, I think the main advantage of wider tires is comfort (at lower pressure) rather than an increase in speed.
Also note that a larger contact patch (due to lower pressure) results in slower tire wear. More rubber on the road means less shear force per unit area of the rubber, and therefore a slower rate of rubber being scrubbed off the tire. This scrubbing is how tires wear out.
A larger contact patch should also give better traction.
No doubt the ACTUAL mounted/inflated size of many (most?) tires differ from manufacturer stated size- sometimes by 2+mm wider than spec. Always best to check for clearance on YOUR bike & rims. The limit for my rim-brake roadies is ~27-28mm actual measured tie width. Before investing in new tires I try to check on-line reviews & local bike club riders to get the best size (& ride/durability) for my needs, especially at today’s prices.
I swapped out 23m rims and tires for 25mm rims and tires on my Ti bike. After the swap, I couldn’t descend at more than 20mph without the bike going into speed wobble (bike was fine with the 23’s at up to 40mph). Needless to say, after that scariness I went back to my 23’s and have never tried anything wider. Any advice on how to debug this?
Hi Timothy and sorry to hear about the high speed wobble. Since your bike did NOT wobble with your old setup and did wobble with the new, it strongly suggests that something’s wrong with the new stuff.
I don’t know enough about the new wheels or rims (not sure if you rebuilt with new rims or went with a new wheelset) to be able to suggest what might be wrong. But, wobbles can come from many things such as loose wheels, loose hub bearings, defective tires with crooked tread, improperly seated tires, loose spokes, etc.
If I knew more about the setup I might be able to come up with some ideas. But one question is why you didn’t just put 25mm tires on the wheels you had? That would be the easy way to go to wider tires.
Happy to try to help more if you can explain more,
Jim Langley
Timothy: Wow, I’ll bet that was unexpected and a bit scary.
You say that you swapped out both tires and rims (wheels?). In that case, it could be the wheels rather than the tires. To check this, try putting the 25mm tires on the original rims/wheels. This should indicate whether it is the tires or the wheels which were the issue.
Thanks Walt (also replying to Jim): I frankly didn’t know you could put 25mm tires on 23mm rims, I’d have though the tire bead wouldn’t seat correctly. I’ll give that a try.
The wheels I switched to were brand new Specialized Rovals. (The other wheels I use on this bike are Easton EA70s and Rol Race SL’s, both using 23mm tires.) It’s possible the Rovals weren’t true from the factory; or that I didn’t have them inflated to the proper pressure (I did notice the front tire squishing around during the wobbles).
Wider tires are taller, the brake caliper will limit the size. Wider rims (20mm inside) will cause a 25mm tire to measure 28mm. You then drop the pressure to compensate for the increased volume of air. Use TPU tubes to reduce punctures (slime is too much work unless you wear out your tire within 1 year). Make sure the TPU tubes are compatible with rim brakes. Use talcum powder inside the tire & on the tube so the tube can move around inside the tire, this decreases rolling resistance.
Went from 23s to 28s when I had to replace a damaged Kestral with a new Orbea Orca. I like the feel and don’t care about speed. What kills me is that the ready for tubeless-ready Fulcrom 600 rims make it impossible to mount and dismount ordinary tires. Riding on shop-recommended Vittoria Corsa Pros, which I can, with difficulty, get on and off. But I am flatting way too often now with the very soft construction of those tires. Oh if only I could get the old Gatorskins! Suggestions?
My non-scientific method regarding tire and rim sizes is to try things to see what works. I”d have tried the 28s on the rims you had the 23s on. It might not have worked, but if it did you could use Gatorskins in 28 size. My road bike came with 25s which worked fine but after some back surgery, I was looking for a less bumpy ride, and put 28s on the same rims. They fit and worked well.
My touring bike came with 28s, which I eventually switched to 32s on the same rims, and later still when successfully to 35s on the same rims.
Jay: I understand and have also had significant difficulty removing tires (especially Gatorskins) from tubeless ready wheels. The only suggestion I have is to go back to non-tubless ready wheels.