Choosing tire size

[Rod Smith]

The correct size is 28.

[Subby]

My 23s (Continental Grand Prix Supersonics with Black Chili) are the best road tires ever. Like riding on unicorn fur. Then I cut across a sidewalk, got the front tire caught in a seam, and went over the handlebars. Now I ride 38s and I could ride over a dead body and not know it. I think the sweet spot is somewhere in the middle. I have 32s (Continential Gatorskins) on order from the UK (I order from Europe because I’m a douche OR because that was the best price I could find…one or the other).

Also I had 32s on my first commuter and nothing bad ever happened so I am sticking with my scientifically significant sample size. 32s ftw!

[rcannon100]

I ride Michelin 700c x 28 at 84 psi, with reflective sidewalls.

Pro: The start of this conversation: potholes. These tires can smash into anything and are fine. Great city tires with the added plus of those reflectors.

Con: They feel mushy and slow.

I went to 25s once and quickly got a flat, but I think it was just the wrong 25s. I would be very keen on moving to tough 25s with a higher psi, in the vain hope of getting just a wee big more speed out of the bike. So… reading people’s comments very closely.

700c 28 at 84 psi is definitely a good solid urban commuter tire which can take the bruising of city life. And after all, it may just be me that is mushy and slow.

[hozn]

@mstone 70384 wrote:

You spend most of your post explaining that size doesn’t matter, then end by saying that you only like a certain size. :confused:

I didn’t say it doesn’t matter, just that it is of limited value without context.

I think it is true that tire type typically changes after 28mm, though. Some exceptions (like Gatorskins), but most tire choices available in a 23mm size aren’t available in a 32mm size. I don’t have a specific size I use for commuting; I simply prefer to run the “faster”-type tires, which means <= 28mm. This is, as i think vvill pointed out, also constrained by rim width. But, yes, pressure is probably a helpful metric. And pressure can be reduced by going larger volume, using wider rims, or running tubeless. Or just pumping up your tires less, if you ride carefully and/or don’t have to deal with pinch flats. With both width and pressure the tradeoff for going bigger or softer is going to be decreased steering responsiveness (or increased squirmyness) as the tires have more lateral deflection (the “light bulb” shape vs inverted U shape). So optimum size for cornering performance is likely something as wide as your rim. Obviously at the end of the day tire choices, like everything else, tend to be pretty individual. Even if everyone agreed that 32mm in brand X might be the best tire for comfort, durability, grip on a specific route, that probably isn’t the best choice if the commuter is also the recreational road bike and also want a tire that is going to be appropriate for faster weekend road rides. To the original question, if you have been riding 23mm tires and it has been working fine, maybe try out 25mm or even 28mm. And maybe choose something more supple than the Gatorskins that still has good flat protection — something like the GP 4 Seasons seems like a solid single-road-bike choice (can find these for half of retail price online).

[mstone]

Right, so it sounds like your preference has basically nothing to do with the width per se, and is mostly about tire selection. There are definitely more limited choices for fast tires in higher widths. That said, if someone is looking for a tough tire that limitation is moot because the fast supple tires get that way with a paper thin sidewall. If you’re choosing something with a more durable sidewall, that–rather than the width–will be the dominant factor. People have told me they really like the ride on the 32-622 Grand Bois Cypres Extra Leger, but they’ve also told me that ripping out the sidewall on an 85 dollar tire makes them sad, so I don’t know that I’d commute on them. I think that Continental coming out with the GP4000S in 28 is a sign that the industry is loosening up a bit in its focus only on narrow tires for road use, and hopefully there will be more choices in coming years.

[hozn]

@mstone 70384 wrote:

You spend most of your post explaining that size doesn’t matter, then end by saying that you only like a certain size. :confused:

@mstone 70404 wrote:

Right, so it sounds like your preference has basically nothing to do with the width per se, and is mostly about tire selection.

I think we are in perfect agreement

[KLizotte]

Love this thread since I’m a newbie and learning a lot. I’ve got 5,000 miles on my Armadillo Elites All Condition 25s without a single flat (the exception being when the back tire started delaminating due to a manufacturing default). The max psi is 120 and I fill them up to about 118. While I love the flat protection I have learned the hard way that they have very little grip and will tend to slide out on the slightest slipperiness.

From this thread and a few other blogs, I have learned that flat protection = less grip because the sidewalls must be extra stiff to provide the former. Someone once quipped that a cyclist could ride on the Armadillos without any air! I can’t comment on how the Armadillos feel compared to other tires since I’ve ridden only on these all year round on all surfaces.

Right now, it looks like the Conti 4000s 28s might be a good choice when they come out (more grip, softer ride for reasonable flat protection). The consensus (?) seems to be that Gatorskins don’t offer as much grip. Schwalbe marathons get good reviews too it seems. Unfortunately I only have one bike at the moment so am trying to find a good balance between speed and reliability.

[jnva]

After I wore out my armadillo tires, I cut out the bead and put it inside I larger tire with a thick downhill tube. I’ve been running over all kinds of junk on the road and so far it’s working well. Of course you pay a substantial weight penalty to prevent flats…

[mstone]

The flat protection and the sidewalls aren’t necessarily related. The GP4000S has fairly thin sidewalls (they’re actually fairly notorious for sidewall tears) but also a thin anti-flat strip. A thin strip like that will stop most road debris from going through the tread without affecting the ride too much. There are some really hard/sharp things that will penetrate a thin strip, so some tires use a thick plastic strip on the theory that something like a goathead thorn might be able to puncture it, but not get all the way through the thick liner to actually hit the tube. You can definitely tell the difference between the thin and thick anti-flat strips. Back to the sidewalls, try going to a shop and compare the GP4000S sidewall to the GP 4 season, which has a reinforced sidewall in addition to the anti-flat strip–that’s the big difference in how those two tires feel. Then compare those two, which both have fairly flexible sidewalls, to a touring or mountain tire, which is more like a car tire. In general, the thinner the sidewall the nicer the tires feel, but at some point they’ll tear if you look at them wrong.

Grippiness comes more from the tread material–a harder material will be less grippy, but longer lasting.

All of this stuff is a tradeoff–you need to balance the road feel against the durability. You can have something that rides real nice for one season or you can have something that never flats and lasts forever, but nobody has magic that will give you everything in one tire. (Back to the OP’s request for not talking about specific tires–sorry, that’s the heart of the matter, and it’s an extremely personal choice.) Some people rave about the schwalbe touring tires, and how they can go 15k miles on a set with no flats, and all I can think is “yeah, because it’s like you’re riding on a hot wheels tire”. Others look at my do-everything tires (conti contacts) and think they’re also too stiff. (But then I look at theirs and think, “man, I’d burn right through those tires with my loading”.) Nothing to do but try a bunch and see what works best for you.

[KLizotte]

^^That explains things far better than anything else I’ve read! Thanks.

Lordy, buying tires is like trying to find a sexy pair of high heels that don’t hurt your feet (something that doesn’t exist by the way).

[mstone]

That’s why I stick to flats!

[Raymo853]

@KLizotte 70408 wrote:

The max psi is 120 and I fill them up to about 118. While I love the flat protection I have learned the hard way that they have very little grip and will tend to slide out on the slightest slipperiness.

I cringed at your high pressure. I really recommend you try lower, like 95. It is a myth that higher pressure reduces rolling resistance, it actually increases it in the real world full of imperfections in road.

Sent from my iPhone using Tapatalk

[jrenaut]

As expected, this thread has taught me a lot about available choices and given me a better idea of how to choose. I maybe wasn’t asking exactly the right question at first.

I think I will probably try 28s. And I’ll probably stick with the Gatorskins because they’ve served me well so far. Thanks, all, for the advice.

[KLizotte]

@Raymo853 70427 wrote:

I cringed at your high pressure. I really recommend you try lower, like 95. It is a myth that higher pressure reduces rolling resistance, it actually increases it in the real world full of imperfections in road. [/URL]

I checked my tire sidewalls and it says the recommended psi is 115-125. Do people routinely go less than the manufacturer’s minimum? I’ve always been worried about pinch flats as opposed to speed issues.

[DismalScientist]

You could probably get away with less, but if you were larger, I would worry about pinch flats. Since the manufacturer doesn’t know who will ride, the recommended minimums are likely more appropriate for larger riders. However, I would suggest going with a tire with lower recommended pressures, which might lead you to a wider tire, although I doubt you bike would take more than 28s.

[Author]

Posts