One Wheel

Right now I'm running tires marked 32mm, measuring 30mm, on 14mm internal width rims (clinchers, tubes, rim brakes). Those tires have served me very well, but are close to the end of their lives. The mechanic at the bike shop said I should be fine to run whatever will fit the frame, but I can fit an 8mm Allen wrench between the current tire and all potential contact points, which suggest that 45mm would fit fairly comfortably. How big would you go on that rim? 35? 40? I got the rims with a bike that only had room for 25mm, and switched them to a frame with more space. I'm hoping to wear out about 1 more set of tires before I replace the whole rig.

Most of my riding is pavement, the 30/32mm work on all the gravel I've cared to try but maybe not as well as I'd like. I'm running 55psi front, 62 rear.

ScottCommutes

If you want to go really wide, you could buy one and see how it works out on the front and rear before you buy the other.

grolby

We used to run 2” MTB tires on rims that skinny, it’s no big deal.

One Wheel

What kind of pressures were you running?

Russ Roth

I ran 45-55 depending on the level of rockiness to prevent pinch flats, 14" internal at the rim with a 2" tire had a lightbulb effect that pinch flatted much easier.
On my ride around bike/single speed commuter I like running a 35mm tire, which I tend to run at about 75psi. I ride it all over NYC/LI and find it to be quick and comfortable at that pressure, though I run it with an 18mm rim, I'm doubtful that I'd go much more pressure than that even with a skinnier rim.

mstateglfr 

You are running tires that are 30mm right now and have 8mm of space between the tire and contact points, and you think a 45mm tire will fit comfortably?
I would check that math, or maybe you and I have different definitions of 'confortably'.

If you run 32mm tires that measure 30mm right now, they are good in unpaclved sections, and you ride mostly paved roads, I wouldn't go a lot wider, simply because there isn't much to gain.
Maybe a 38mm tire since it would likely measure closer to 35mm on your rims.

One Wheel

8mm clearance on all sides, could go 8mm x 2, but that would rub a bit. 32 + 16 = 48mm would rub, 45 is probably safe especially figuring that it will almost certainly inflate smaller. Not saying my math is right, that's just the math I did.

38 seems like a reasonable figure to try. Definitely looking for a slick, not a knobby. I'm liking what I see for Panaracer GravelKing Slick, Rene Herse (Barlow Pass) and also Continental GP 5000 but those only go up to 32. Any recommendations between those or something else? Teravail Rampart is also available in 38, and has the advantage of being the same model that's served me well in 32.

mstateglfr 

If your tire is 30mm wide and there is 8mm on each side, that's 46mm of space. A tire that is 45mm wide when spacing is 46mm is crazy tight. Even if the tire is 45mm and measures 43mm, that's still crazy tight to me on a gravel bike since it's only 1.5mm of space. Clearance that tight would create scraping for me even on regular dry roads.


A GK Slick is pretty solid for a mix of price, durability, and rolling resistance.
Continental Terra Speed in a 40mm rolls fast and that model line tends to run narrow. So between the narrow rim and undersized width, that could work.

ScottCommutes

Agreed. I don't see a whole lot of upside to trying to squeeze in the widest tire that you possibly can. Give yourself some room. If you are currently at 8mm clearance on each side, consider perhaps reducing that to 4-5mm.

One Wheel

Thanks! I'm a little hesitant to get a knobby tire on account of road noise, otherwise the Terra Speed look great.

It sounded like the guy at the shop was advocating as wide as would fit, which seemed like overkill to me. Sounds like the consensus is that it probably would be overkill, but he's probably right that rim width is not the limiting factor that I thought it would be.

DorkDisk

38 is a good size; not too big and definitely not old school 32.

I'm running 35 GK SS tubeless @30psi, before that I was running tubed Soma Supple Vitesses @45psi. For road, the Somas are nicer IMO - smoother and lighter, and they're also made by Panaracer.

Russ Roth

The one I like to run is the Donnelly x'plor USH though I run 35c not 38. I've ridden them the length of the Erie Canal, the Confederation trail on PEI. Not great on real trails, but for anything resembling a road they run nice.

tFUnK

I would say 35-40mm. You can probably fit 42s but in my experience things start to feel a little heavy once you go past 35mm. On my gravel bikes 38-40mm is what I run, but for pure pavement they do feel sluggish. They're good for the dirt trails I do but like you I feel slightly underbiked (but my frame clearance is limited to 40-42 and 42mm feels way too heavy/slow on the road to me).

If you're used to 32s and like them for pavement then you may want to just try 35. If you just want to get a sense of how a big boy tire feels, then go for that 42.

t2p

another vote for terra speed - great tire - roll relatively well despite being a raised tread (knobbed) tire

as others mentioned, they can run small - mounted 35’s were close to 33 mm and 40’s are close to 38 mm


also like some other tires including GK SS, S Works Pathfinder, Tufo Speedero and Thundero

etc etc etc

79pmooney

A couple of things to consider"

Tires grow with age. They are fabric and virtually all fabric stretches or settles if stressed long enough and unless you deflate your tires after rides, they are always stressed. And spokes break. From poor builds, fatigue and things happening; sometimes while riding. If your tire won't get past the fork or stay after that spoke breaks, you aren't riding home until you replace the spoke or re-true the wheel. More clearance helps both htese issues.

NumbersGuy

I've just put a set of 700x38 Gravel King Slick Plus on my gravel bike for mainly road riding and have been very happy with how well they roll on pavement, while also giving me something that will be able to handle lighter off road duty as well. I run 700x35 S-Works Mondo on my road bike and those feel a little faster rolling to me but are probably less suited to off road. Both weight about the same 360g and I feel give a nice overall blend of grip, speed, comfort and puncture protection (I run TPU tubes on the road). Either of these could be a good option that still gives you some clearance.

Kapusta

When you say “rim brakes” I assume you mean cantis?

For what you are describing, I would go with 35-38mm slicks.

I ride mostly a mixture of crappy pavement, chip seal, gravel and dirtrods, (60/40 paved / unpaved), and run 38mm slicks.

One Wheel

This or something very similar is what I'm using:

https://tektro.com/en/product/49

At this point my strong inclination is to go with 35mm Panaracer GravelKing Slicks. I stopped by the bike shop yesterday and they had them in stock from 26-32mm, with the non-slick GKs from 38 up. I'll probably have to order them, but my current tires have a few hundred miles left and I'm out of money.

Thanks!

Kapusta

Have you checked the tire clearance on those?

One Wheel

Yes, the limiting points are on the frame and fork.

Edit: this is the actual brake model:
https://velo-orange.com/products/tektro-r559-extra-long-reach-brakes

And a picture of the tightest clearance point, with an 8mm Allen key next to a 30mm wide tire: