Thought that I'd start a thread on tires for smaller-wheeled bikes, seeing how selection is not as great. Share what you know, add photos if you can. I'll start....

Panaracer GravelKing X1 20" x 2.10"
Just spooned these on yesterday and did a mix of road, gravel, and (dry) singletrack with these and they performed beautifully. Felt quick on the road, stable on gravel, and grippy on the trail. Haven't ridden in wet conditions yet, but first impressions are positive.

Good idea. I'd like to know if there is a more puncture resistant option for my Tern Verge S8i which came with Schwalbe Big Apple tires (which got me only 1,100 miles before a flat); I replaced them with Schwalbe Big Ben Plus (I'm currently at 4,600 miles on that set).

Running 2.2 Maxxis Holy Rollers on a Zizzo Liberte. In the lowest gear, there’s a slight chain rub—never an issue, but not ideal. Rolling resistance is pretty low at 60 psi. For yesterday’s trails, I went with 17 psi up front and 27 psi in the rear.

I used many tires for small wheel sizes ETRTO349, ETRTO355 and ETRTO406.

Some of them, fits the best ones:
- Continental Contact Urban: exists in many sizes, for small wheels 35x349, 32x406, 42x406 and 50x406. Its a lightweight very fast touring tire that outperform several so called speed tires, its long lasting with an excellent puncture protection and its not expensive. Not recommended for rocky trails due yo its thin side walls.
- Schwalbe G-one Allround 54x406: its an excellent folding gravel tire which is also fast on roads. It has a good puncture protection. Drawback: very expensive, I Europe not listed on the Schwalbe catalog, only available from Brompton (the 54x406 size was developed by Schwalbe on demand of Brompton for the G-line).
- Continental eContact Plus: exists in 50x406, 55x406, 62x406. Its a wide tire with a top notch puncture protection, a competitor of the Schwalbe Marathon Plus, but with a much mower rolling resistance. Drawback: like all those tires with a special puncture protection layer, its heavy.
- Schwalbe Big Ben Plus: 55x406, a comfortable, wide balloon tire with a very high puncture protection (but not as high as the Marathon Plus and eContact Plus).
- Schwalbe Big Apple and Big Ben: exists in several sizes, 50x355, 50x406, 55x406, a very comfortable balloon tire, relatively lightweight with a low rolling resistance but a medium puncture protection.
- Greenspeed Scorcher 120: exists in 40x349 and 40x406 high pressure relatively wide tire, the fastest tire for small wheels with a better puncture protection than expected from a slick race tire (it looks like a Kojak but this one is really super fast, has a better puncture protection and last longer). Drawback: doesn't fit on a Brompton with mudguards.

The one i do not like very much:
- Schwalbe Marathon Plus: slow, low grip on the wet, outperformed by the Continental eContact Plus.
- Schwalbe Super Moto: relatively fragile.
- Schwalbe Pick Up: designed for cargo bike, high load but poor puncture protection (I had several flats on the same places where I had none with the Big Ben Plus and eContact Plus).
- Schwalbe Pro-one: 28x406 fast but fragile, I had several of them with side wall cuts and blisters on the rolling thread. The Contact Urban is almost as fast when the weather isn't cold.
- Schwalbe Marathon Green: exists in many sizes 35x349, 44x355, 47x406... strong tire, good puncture protection but stiff uncomfortable, heavy with a bad grip on the wet, I would say obsolete.
- Panaracer Minits Lite PT: 32x406, 23x451 not as fast as expected, narrower than 32mm as announced, good puncture protection for a road tire.

The very bad:
- Schwalbe Kojak: 32x349, 32x355, 32x406 slow, fragile, wear fast.
- Schwalbe Marathon Racer: 35x349, 4x355, 40x406 slow, average puncture protection, obsolete.

I've been using Schwalbe "Marathon Plus" on my Tern Verge S11i (currently in S8i form) for several years, and have only had one puncture though it was a doozy. I added "Mr. Tuffy" tire liners and haven't had any flats since. I'm in Chicago.

Which are you using, 20x1.35 or 20x1.75? The latter, I guess. IAC, how do you find the ride changes from the wider "balloon" tires? (my tern Verge S8i came with 20x2.15" tires) I see the max. psi for the 1.75's are 70 psi, considerably higher than the 55 psi on the Big Ben II's. Seems like you lose a lot of the comfort, no?

Yes, I have the 20x1.75 (47-406). I run them at 50 psi (F) and 60 psi (R), and don't find them uncomfortable. I weigh about 220 with my backpack.
I don't worry as much about comfort on my commute, though I have done a couple century rides on this bike and lived to tell about it.
My Verge is from 2013, and I think Tern has moved to wider tires since then. You could try keeping your wider, softer tires and just use a tire liner.

I'd be interested in opinions on the following: I have a tern Verge S8i with Big Ben Plus tires. I've gotten, thus far ~4,850 miles on them, though the tread is noticeably more shallow (but still ride-able). This bike now serves as my backup or what my wife rides for those infrequent times she comes to ride with me (most likely she will use it more in the future than I will). So, comfort is important for her. Flat resistance is a priority for me. What are my options?

a. Stick with the Big Ben Plus tires and the likely 5,000-6,000 miles I'll get out of them.
b. Stick with the Big Ben Plus tires but add tire liners (if so, which? I've never used them before).
c. Try the Continental eContact Plus tires Jipe recommends?
d. Is there another option?

There is a third option: mount Big Ben Plus they are balloon tires like the Big Ben and Big Apple but with a built-in puncture protection layer (not as thick than on the eContact Plus and Marathon Plus but still effective).

My mistake, I meant Big Ben Plus. Fixed.

5,000 miles without a flat is pretty darn good in my book, so I don't think tire liners will add anything but weight and a slower, less enjoyable ride.

What you have clearly works and should work fine for your wife too.. It boils down to whether or not you like experimenting with something new.

I've used THESE for years. I haven't noticed any degraded performance, but I may be less sensitive than some.
I notice they have an "ULTRALIGHT" version, ribbed for extra sensstability.
As you have seen, these are somewhat controversial.

I guess I got spoiled with the Marathon E-Plus tires on the Montague Allston, 6,100+ miles with no flats and still a significant tread left; I'd expect them to last at least another 2,000 miles. Also, I'm pretty good at checking the tires before each ride, removing all stones/glass/etc. and running them between a certain psi range (front: 50-60 psi, rear: 58-73 psi).

Schwalbe Marathon 365 (20 x 2.15")
A good, all around tire that rolls nicely and can handle trails. But the party trick is winter traction; the compound stays soft in the cold, allowing the tire to still find grip. I've ridden carefully across sheets of ice. Short of studs, this is a good winter tire. And better than studs, this is a good 4 season tire.

I chose these for the Nua Luna. As you'd expect they have way better traction than the Marathon E-Plus (and of course much lighter).

Even with a slight chain rub in the lowest gear, it hasn’t been an issue. I couldn’t pass up buying these again for $27, as they’ve performed well at both 20 and 60 psi.