Stano9

I have a gravel bike which I'm planning on using for my road commute (1hr each way) by changing the tyres. The internal rim width is 20mm and the stock tyres are 38c.

I've read up on widths and see that road cyclists are switching to wider tyres due to comfort and rolling rsistance, but wide in road cycling is 28c. Given my bike could probably take between 28c and 40c, what would you guys recommend I go for?

Bill Kapaun

My personal choice would be external rim width + 3 to 5mm.

tyrion

I'm in the bigger the better camp, but it depends on what you're trying to optimize. I'm mostly trying to optimize comfort.

MudPie

See the below link to Sheldon Brown's article on tire widths. About 7/8 of the way down the page, he includes a handy chart listing rim width and tire widths.

https://sheldonbrown.com/tire-sizing.html

Stano9

I like comfort, but given the ride is about an hour I also want to keep efficiency high. I previously had an old road bike with 23c tyres on it and it was kind of uncomfortable on potholed roads, but I got used to it over time. So I guess I'm trying to stike a balance between efficiency and comfort.

Polaris OBark

I ride 38mm on road (Rene Herse Barlow Pass EL). Rolling resistance is much more important than tire width, per se.

Steve B.

I had 32mm Schwalbe marathons on my tourer used for commuter. I would have gone to a 38 except I could not squeeze that tire under the fenders. I think 32-35 is a nice size as you can get away with 50-60 psi and gain some comfort, yet maybe easier rolling that a 40 or so. It's an art not really a science as to speed vs. comfort.

andrewclaus

Faced with the exact situation a few years ago, I went first with 25 then up to 28, where I'll probably stay. I'm not commuting anymore, but cycle up to 200 miles/week in retirement. My main consideration in not going larger is tire mass. I do a lot of climbing.

I saw somewhere that with that rim width, the wheel is very slightly more aerodynamic with 28 than with 25.

One extra reason for not going larger is that I share spare tires and tubes with my wife. Been doing that for forty years and it's a hard habit to break.

FBinNY 

There's much less correlation between tire width and rolling resistance than most people believe. A 2-inch tire properly inflated has almost identical rolling resistance to a 1-inch tire.

The key is matching tire pressure to payload and road surface so pick a tire properly matched to the rim's width and inflated to about 90% of the maximum pressure listed on the sidewall as a starting place. Then do some test rides.

dsbrantjr

I have 38mm and 47mm tires on 19mm rims with zero issues.

Kapusta

This^^^

RH Barlow Pass is a fantastic tire on the road. And great on gravel.

The 35mm Bon Jon Pass is also really good.

I’ve used both of these for all my gravel and paved road riding, and never wished for something smaller.

RB1-luvr

I have an extra set of wheels for road use for one of my cx bikes, and I use 30c slicks on them. That bike moves along as such, and feels darn close to my more road race oriented bikes, yet a little more comfortable at 60-65 psi.

mitchmellow62

Food for thought: https://www.bicyclerollingresistance...000-comparison

https://www.bicyclerollingresistance...rim-width-test

https://www.slowtwitch.com/Products/...ance_7406.html

pdlamb

If you're using stock tires on a gravel bike, they're probably slower than you want for an hour long commute. Try dropping a size or two and get a supple road tire (with adequate tread) in the 32-35 range. I like the balance between flat resistance and low rolling resistance of the Panaracer Pasela or Continental Gatorskin. (YMMV!)

ClydeClydeson

Depends on the surface you intend to ride. If the pavement is all brand new and smooth as a baby's arse, then narrow 28ish mm tires will be fine. If there are potholes and cracks in the road, or sections torn up for construction, then wider is better. 38mm is a fine width and you can tackle anything you'd likely encounter on a normal commute. I like 32mm tires because they are a bit lighter and there are lots of high-quality tires available in this size. 35mm are a great compromise.
The drawbacks of wider tires are weight, really only an issue when climbing hills, and aerodynamics, especially if the tire is significantly wider than the rim and when riding at higher speeds.

raqball

My fitness / gravel bike came with 40's on it but I've swapped them out for 32's and TPU tubes. I mainly ride on tarmac. I thought about going to 35's but decided to try the 32's and see how that goes.

Have carbon wheels with 19.5 inner width...

raqball

delbiker1 

I most like 28 or 30 mm for pavement. I have a Poprad that I use for easy path/gravel and chores, it has 32mm GK's on it. I tried the same tire in 35 mm, but it was too tight. Reality for me, tires with an actual width, when mounted, of 28 to 32mm are optimal. I still have one bike with 25mm, most 28 are too tight at the fork crown, and when I ride it, I enjoy being on the skinny tires on a classic steel bike, a Lemond Tourmalet.

urbanknight

There are multiple factors to consider, and there is no single right answer here.
1) How much are you carrying? If you have 60+lb of equipment/food/clothes in your bags/racks, you want to go wider. If just yourself and your bike, narrower is fine.
2) How bumpy are the roads? Naturally, wider is good for rougher roads while narrower can be faster on smooth roads.
3) What's more important to you: comfort or speed? (This has already been discussed)

I have had two vastly different commutes, so I had two vastly different ways of doing it. When I rode to work every other day, 21 miles and ~1200' of climbing each way, and drove my clothes and stuff on the alternate days, I used my road bike with skinny tires and wore my lycra kit. When my commute became a daily 6 miles pancake flat, I put 1.4" slicks on a mountain bike and carried my stuff in a child trailer while wearing my work clothes.

hokiefyd 

In support of this: Why wider tires are NOT slower – Rene Herse Cycles

He also opines here about how drum tests are not as reliable as road tests: How We Test Tires – Rene Herse Cycles

That's all just Jan's opinions and experience, sure...but he has some compelling data as well.

70sSanO

Since you have the bike and you know where you are going to commute, ride it with the current tires and get a feel for comfort vs speed.

You will need to balance whatever you get with the need to reduce getting flats. Which might bring tubeless into the equation, if the rims will allow for it.

John

FBinNY 

Understanding the relationship between tire width and rolling resistance requires on focusing on what's happening where the rubber meets the road (so to speak).

Rolling resistance has two main components; friction between the tread rubber and pavement, and energy losses due to flexing of the tire itself. Start by looking at the contact patch, who's area is roughly equal to axle load divided by air pressure. This is true regardless of width, but the SHAPE is determined by width and is critically important. On narrower tires the patch is narrow and needs greater length to establish the area, while wider tires have rounder, wider, and shorter contact patches.

Long contact patches mean greater vertical tire distortion (imagine a secant line through a circle), and therefore more internal friction within the tire. So, reduce resistance by using wider, supple tires with thin tread rubber thickness. OTOH, wider tires will be heavier, and will increase air drag (more meaningful at higher 20"mph speeds), and that should also be considered, along with things like the road surface itself because you don't want to be walking home.

FWIW- my commuter, built on an MTB frame has very light 1.9" skinwall tires, and the rolling resistance compares very favorably with the 1" tubulars on my high end road bike.

So, throw it all into the hopper, shake well, and see what's best for your personal needs.

BTW- one of the reasons for narrower tires historically had nothing to do with the tire itself. Bikes used caliper brakes which had to reach around the tire to reach the rim. Big tires needed bigger brakes reaching farther from the mounting bolt. Narrow tires improve brake performance by allowing shorter, stiffer, and lighter brake calipers. Cantilever, V-brake and hub brakes free us from that design consideration.

Yan 

If your commute is an hour each way and it is on paved roads, I would use no wider than 28. There is simply no reason to sacrifice speed in exchange for more comfort when you are already riding on paved roads. Just go with a fast tire and get home faster. Even 25 is fine in my opinion.

t2p

Panaracer GK SS 700x35


Conti Terra Speed 700x35


Conti GP4S 700x32


many good options - including tires mentioned above in this thread and I listed a few below

I've used the following tires / sizes listed below and included some pics of the tires (mounted)

Continental Grand Prix 4 Season - 700x32

Continental Terra Speed - 700x35, 700x40

Panaracer Gravel King SS - 700x32, 700x35, 700x38

.
edit: @ 260 lbs would not recommend above tires

( but *maybe* Terra Speed in 700x40 or GK SS 700x38 )

mattkime

What wheels / rims do you have? I run some 23s on wheels with the same internal width - not what I'd recommend but you have options.

How much do you plus bike and gear weigh? Use this mainly to make sure you're not going too narrow AND that you're using the correct tire pressure - https://silca.cc/pages/sppc-form
I'm partial to GP5000 tires as a great balance between speed and durability, which is to say they're a fast tire that is also very durable. I'd get them in the largest size which is 32. Do you run tubeless? Then you might want to consider the tubeless version.

GP 4 seasons last a bit longer. Gatorskins are recommended if you need to avoid flats at all costs.

To frame whats at stake - you might be happy with anything recommended in this thread.