The obvious answer is that there is no such thing. Everyone has a different idea of what an optimal tire width and that has a lot to do with the kinds of roads you like to ride (paved only or paved plus gravel) and the amount of weight you carry (minimalists can use skinner tires).

But what if you're not a minimalist in terms of weight and you like the idea of doing a gravel road from time to time?

The old standard for touring was 700 x 32c (or 27 x 1 and 1/4). Road racing tires have been getting fatter and so have touring tires. Some very good touring frames can't handle much fatter than a 32c and fenders, some can.

I'm thinking that a touring bike that can handle a 700 x 38c-40c tire (or the 26 inch equivalent) and fenders is probably optimal if you're not a minimalist in terms of weight and you like the idea of touring on gravel roads.

700 x 28's worked for my tours.

29 x 2.3 or 65 mm worked well for my last tour. More kind of bikepacking. Some pavement, lots of dirt paths and roads, crazy NH class 6 roads( think washed out jeep trails) and some sweet single track, mostly tame. A mostly slick tire with some sipping and inverse tread.

Nailed it!

Yeah that's a really fat tire. Which bike did you use? If going drops, you'd almost have to use a salsa fargo for touring or the velo orange piolet to run a tire this fat. Lots of choices if running flat bars as this is running into mountain bike land in terms of tire size.

I was hoping for a bit of help,

I don't have any issue on gravel with my 1-1/4s (32). Works for the occasional few miles in dirt and mud, too, assuming nothing too ridiculous.

Way fat. Karate Monkey with 35 mm rims. Front sus, flat bars with bar ends, very comfortable and a variety of hand positions. Fit fenders and a rear rack( just) Air up for pavement, drop down some psi for extended dirt/trail. Set up works very good.

Every time I've upgraded to wider tires, 32 to 35 and now 38, I wonder what was I thinking riding narrow tires. The only reason I've stopped at 38 is that my bike can't take anything wider and still have room for fenders. The more comfortable the ride the less fatigue one will experience, an important part of touring as far as I'm concerned.

Sorry, couldn't resist. The right answer is, it depends. Wider the better on loose gravel, roots/rocks and washboard, where you can let out a bunch of air. Hardpack or relatively smooth roads or trails allow you to go skinnier. In my view, it's all about volume. If I had to choose a good compromise in 700c, 35-40 would be nice for both on and off road, but ideal for neither.

I always have used 32s but always wanted wider. Hence the new bike with 35s. I may go to 38s if these aren't too fat.

My daily ride and would-be touring bike is running 50-622 Schwalbe "Kojak" tires. It also has dual suspension, tuned for street use. The 15-degree pull-back MTB bar is two inches higher than the nose-less Adamo seat. The gearing is Shimano 3x10 with a 16-105 gear inch range. It also has hydraulic disc brakes. When I go touring, I'll pull an Extrawheel trailer.

It is the most comfortable bicycle I've ever had or ridden and I am perfectly willing to give up the bit of extra drag and weight all this entails for the minute-by-minute and day-by-day performance and comfort this bike provides.

Touring bikes are going in this direction -- thanks to the developments cascading down from mountain bike development.

I am too old and too broken to ride a racing bike anymore and I suspect many of you are too. Why not slow down, look around, take it easy and enjoy the ride?

Joe

Clement X'Plor MSO 700x40c came on the 2017 Sutra I bought. I do not know the knowledge behind Kona's decision to spec this size for this model. However, I have thoroughly enjoyed these tires on the road and my gravel roads. When I hit a piece of gravel and it moves, I have confidence.

Agreed. Most of my gravel road touring has been on 23mm tires mainly since the bike I use most doesn't accept anything wider. Worked fine and no problems with the tires (did need to make sure the pressure was high enough). I've also done some touring with another bike that currently has 35mm tires, but I'm not sure any of it has been on gravel.

Don't ask me!

bikemig, There just isn't an optimal tire size, in height or width. There, I wrote it.

On my two Cannondale (700C) touring bikes I've used 32, 35, and 37 mm tires. The 35 mm tires were Panaracer Crosstowns and wide enough to almost touch the chain stays whereas my 37 mm Contis have plenty of chain stay clearance. The Crosstowns really bridged paved and non paved surfaces, but were very heavy and an epic battle to mount and remove. The 32 and 37 mm tires feel very similar with a load with the comfort nod to the 37 mm tires unloaded.

My Trek mountain bike has some 26"X1.95" Conti dual tread tires that work great on hardpack and acceptable on pavement. Not so great in mud...

No matter what tire, tire size, or tread is chosen, there are some concessions for riding outside of it's intended element. My next set of tires will likely be 37 mm Gatorskins or something similar.

Brad

I know people tour on just about anything. Really, for me, whatever I settle on for my commute tends to end up as my touring tire as well. I started with 700 x 32. Tried to go thinner with 28s. Decided that was less comfortable, so I went back to 32s. Then 35s. Then I ended up on Vittoria Randonneur hypers in 38/40 (depending on where you take the measurement from). At that point, I couldn't go any wider without replacing my fenders. Never had a desire to go narrower. Instead I replaced my bike, which now has 26 x 2.15" Big Bens. Daily commuting, plus it's been on some long, weekend bike-camping trips. They're great for pavement, and they don't mind dry hardpack, either. I'm hoping to bike the GAP & C&O this year, and I wouldn't hesitate to use the Big Bens on that that trip, from everything I've read, but I'm also building up a "26 plus" wheelset, and I'm considering using Surly Extraterrestrial 26 x 2.5" tires for the trip. I guess if I keep on this way, in a few years I'll be riding a fat bike with 5" tires everywhere.

As technology in tires has improved, we now have lighter and more flat resistant tires than in the past, and so giving us the option of going wider without much penalty. For decades, I rode 28's but now use 32's as my standard, but.....I can't say that I haven't been tempted by some of the newer lighter 35's out there.

Btw Max, that does look fun but are your tires wider than your crank ?

I have not had the opportunity to tour "yet", but, I have acquired a new bike and have been prepping it, accumulating needed gear, and educating myself about it for months now. So I can't speak on actually multi-day touring, but from my experience along this journey so far, and the day rides I have done on various terrain, I can say that I'm very happy with the 48c width tires that came stock on my bike, and will be sticking with it or as close to it as I can depending on what tires I get next.

No argument on your setup as it clearly works for you and thats the only thing that matters in an individual basis.
But when looked at overall, i cant say i have seen touring bikes moving towards dual suspension bikes with bars 2" above the noseless saddle.

Touring bike is a very wide category and encompases anything from a drop bar road bike with modified gearing and geometry to a 27.5+ rigid mtb and many different setups in between.
Dual suspension frames with high bars running on 50s for street use seems more like a specific setup than an industry trend.

Perhaps i am missing something or not thinking of some segment which is trending towards a bigger part of the market.

I have extremely limited experience, so probably my input should not be weighted very much. However, I have been happy with the 29 x 2.1 tires that came with my Ogre for a short multiday trip on pavement and a flooded dirt and gravel trail, as well as riding 30-60 miles almost every day on pavement from spring through fall. (I really have gotten rather lazy this winter.) The Surly Extraterrestrial tire in 29 x 2.5 is finally available, and my LBS ordered me a set, which is due in this week. Hopefully my fenders will still fit and there will be no rubbing. At my advanced decrepit age, I am all about comfort.

mstateglfr:
Yeah, much of what I described is simply what I have and not, perhaps, what I'd buy if I had the money.

mdilthey's rig is closer to what I might build; those very big tires would make a huge difference in comfort and go a long way toward compensating for lack of suspension. I wouldn't need a trailer then either.

My general point & where I think touring is headed is that travelers are seeking more comfort and less race worthiness. Check what the Europeans are doing; they are way ahead of us in this regard.

Joe

I think 28mm tires is the minimum for touring.
Sometimes you will fined yourself on none paved road, and with heavy gear maybe better consider 32mm tire for safety.

As most other allude too, it really depends. I always appreciate the folks who just go and ride whatever the hell they have, 23c racing tires or 45c special touring tires or anything in the middle.

For road touring I think the best seems to be in that 32-35c range. It offers a good blend of flat prevention, efficiency and comfort.

After riding from Glasgow to Nice last summer, almost all on paved roads, I would never ride on anything less than 38mm. I just don't see what the point would be of riding on narrower tires.