DeadGrandpa

My road/gravel bike is 700x40 also, and it was a little sketchy on certain sections of the Denali Hiway. I probably would have had better results if I had lowered the pressure first, but I know that now. My dedicated gravel/strictly off-road bike is 29x3 and it's totally awesome. Not so much on pavement, though.

xseal

agree. 40.

twowheeldesign

Agree with everyone running 40-43 tires. Currently on 43 gravelking SK's, and love the comfy ride when I air them down to 30-32psi on the native-surface roads in Northern CA (read: lumpy/rutted). If I was grinding farm gravel I would still choose 43s for the comfort!

DomaneS5

The 700 x 40c WTB Nano tires on my gravel bike are perfect, IMO.

ofajen

I don’t race, so I can choose the luxury of running my vintage MTB with 26x2.2 (559x64) Race King Protection. They are so comfy, enough tread to deal with winter messiness and surprisingly fast. Our gravel roads tend to have fairly big rock and I prefer big tires.

I also ride 700x32 sometimes if I’m just riding roads and crushed stone trails but would prefer a bit wider even for that.

Otto

tangerineowl

Conti RaceKing Protection 2.2" if they fit.

ofajen

I ride the 26er version of this all winter long. 👍

Otto

l3m4nt

somewhere between 2 - 2.3

iancredible

Gravel's such a wide spectrum of surfaces and preferred speeds that people ride at--for me, my gravel bike is more like an all-road bike. I like to ride fast, near road riding speeds. Over the bike's lifespan, it's probably seen 80% pavement and only 20% gravel, and <1% singletrack. Therefore, I run 35mm G-One Allrounds. This works best for me--it allows me to maintain decent road speeds but it's ready when the surface turns to rural dairy farmland gravel roads or rails-to-trails packed limestone. If the trip is going to be <12 mph on more technical terrain, then I have a rigid flatbar 29"+ bike with 3" wide rubber to handle that.

Noonievut

I'm going to work on a proprietary formula (lol) that takes into account % time split between paved, gravel roads, singletrack; 'chunk or condition' rating of each of these surfaces; plus some factor including rider skill, whether coming from a road or mtb background, and desired level of comfort (wuss to crazy). That's version one. Follow-up version will take into account road/trail surfaces in a circumference around where you live/ride.

iancredible

What would the formula output? The ideal tire width?

scottfsmith

Re: a formula for tire width I would say the surface quality is #1. They have gravel rating systems out there already, I think there is a 1-4 and a 1-5 system in terms of smooth to chunky/rooty. Google coughed up this 1-5 system for example.

Also speed is an issue.. I like to take gravel at near-road speeds, the thrill is what makes it fun. But some riders don't have that goal.

And, including the other elements you mention would be helpful.

I am personally only on grade 1/2 gravel on that system I linked, and my current tires are 700x35c on 25mm ID rims with 37.2mm actual width .. they are totally awesome for that level of gravel and my speed/comfort goals.

N2deep

The width of tyre directly depends on the size of the gravel, rider weight, compaction of the soil, soil type and rider experience. The fast guys at the Hico 150 rode 28s and 32s and averaged +20 mph, 135 gravel/hard-pack and 15 paved, wow. I rode 35s. Interesting discussion.

scottfsmith

Thats interesting to hear, I was trying to guess tire sizes from watching the videos of that race on Youtube (great videos BTW! - search for gravel locos to pull 'em up). Dylan Johnson in his video said he was on 44s, I was personally wondering if he could have topped his #4 finish if he had something a bit smaller.

N2deep

Sorry, I didn't intend to mislead anyone, yes there were a lot of riders with fat tires. Personally I think for me 30 or 32s are perfect for dry hard packed roads and 35s to 40s for sandy or muddy surfaces. Look at the videos of the Sulada Roubaix or the Hico 150

ericcox

I was on 33s at Hico (only the 100km). For most of the gravel riding I do, 33s are fine, though I will probably replace these with 35s when the time comes.

dgodave

50mm min (on 650b). Sometimes I get caught up in some singletrack or other rough stuff.

franswa

I enjoy having 47s on my 650b for this exact reason, so this would be my minimum. I have a set of 650x48s when it's time to switch out. For 700c I would like to stay above 42s.