Minimum tire width to avoid flats on rough gravel?

[moose8]

My road bike is probably my favorite bike to ride, but it will only fit 25s for tires (which is what I use). I have been using Schwalbe Ultremos, and on the road they have never flatted, but on rough gravel they definitely have more than I would like, and generally only when I am really tired and don't want to change a tube. Should I just use my bike that fits 32s on these kind of rides, or is there a magic tire that won't pinch flat under 185 pounds of mediocre cyclist on bumpy, rutty gravel roads? By way of specific example, I have flatted a few times on the roads at d2r2, but I have never flatted when using my much heavier bike that has 32s.

[JStonebarger]

What pressures are you running? Enough psi in there and no tire will pinch flat!

[redir]

ON rough gravel I'd probably use my cross bike with 32's. The gravel roads in my area tend to be suitable with 25's unless they just lay it down fresh. It's kind of a double edge sword, in rough gravel you just use big tires and deal with the occasional pavement or packed gravel in smooth gravel roads you can use 25's no problem but it's always that errant piece of gravel that gets ya. Going a bit heavier on the pressure helps too.

[MattTuck]

I think 25s should be good enough, assuming you have a hard wearing tire and keep the pressure high enough to avoid pinch flats.

[moose8]

I think I usually have them between 105-110 if I remember correctly. It seems to be the stray big sharp rocks and/or potholes that do me in. I keep thinking in theory they should be fine, but then in practice they are not, whereas the wider tires never have given me a problem on the exact same roads, but they have the downside of being on a bike that doesn't make me smile as much while riding it.

[Ken Robb]

I guess your gravel must not be very deep or else 25mm tires would dig in and the ride wouldn't be much fun. Some years ago I tried 700x23 or 25 (I forget) Specialized Armadillos. They were tough and stiff. I never got a flat but I didn't keep them long because the ride on pavement was stiff and dead. In retrospect I think I should have tried them at much lower pressure than the 115 psi I thought was proper back then. I wasn't riding them on gravel so their toughness was not worth the other tradeoffs to me.

[moose8]

I guess your gravel must not be very deep or else 25mm tires would dig in and the ride wouldn't be much fun.

It's east coast dirt roads, mostly in Maine and Massachusetts. Lots of packed dirt and potholes and rocks - the deep gravel only tends to be on the soft shoulders, which are pretty miserable to hit no matter your tire width - they kind of grab you like slush.

[GRAVELBIKE]

Are you slashing sidewalls, pinch-flatting, or just plain puncturing your current tires?

[MattTuck]

I guess your gravel must not be very deep or else 25mm tires would dig in and the ride wouldn't be much fun.

Gravel/dirt roads have two dimensions, in my experience... smooth - rough, and hard - loose.

Loose surface (either because of the stone, weather conditions, recent grading, etc.) is crappy to ride whether it is smooth or rough.

You can still have very rough surface that is hard packed.

[merckx]

Conti GP 4S is a damn tough tire. They run a little narrow so you may be able to stuff a 28c in your frame. The actual width is about 26mm.

[moose8]

Are you slashing sidewalls, pinch-flatting, or just plain puncturing your current tires?

pinch flatting I believe; the tires seem more puncture resistant than other tires I've had.

[GRAVELBIKE]

pinch flatting I believe; the tires seem more puncture resistant than other tires I've had.

If you're pinch-flatting on tires that are pumped up to triple digits, you probably need to be riding something capable of accommodating wider, higher-volume tires. The smallest tires I ride off-road are 28mm (actual), and I run them as low as 50-60psi (I weigh 195#). Granted, I'm not bombing rocky trails with that setup, but I'm certainly not afraid to venture off the paved roads, either.

[Gummee]

I've pinch flatted everything from a 23c to a 34c tire riding gravel. If you hit that one rock 'just wrong' it'll happen to anything.

If you must ride small tires, get the biggest tubulars you can. No pinching.

HTH

M

[bcm119]

I'm not sure if it's possible to pinch flat a tire pumped to 105+ with 185 lbs. Sounds like maybe the rocks are just slicing the casing.

[roydyates]

It's east coast dirt roads, mostly in Maine and Massachusetts. Lots of packed dirt and potholes and rocks - the deep gravel only tends to be on the soft shoulders, which are pretty miserable to hit no matter your tire width - they kind of grab you like slush.

So the answer should depend on whether you are in mud season or not? Right now, there are probably some roads where even a super fat tire won't be enough.

[Liv2RideHard]

I just did Rouge Roubaix. My set-up: Ambrosio Nemesis tubulars with 24mm Veloflex Roubaix's. Ran at 80 psi front and 82 psi rear. We were racing the gravel sectors. Gravel was loose for the most part. Not a single flat with the hammer down over the gravel sectors.

My brother ran Williams carbon clinchers with Conti Gatorskins and latex tubes. He didn't have any issues over the same gravel sectors.

[Johnny P]

conti gp 4s is a damn tough tire. They run a little narrow so you may be able to stuff a 28c in your frame. The actual width is about 26mm.

+1

[NJC]

Like the previous poster, I have found the Cont GP 4s to be generally tough enough for gravel and smooth fire road in 28mm - I have not flatted, but did get eventually develop bulging after a particularly rough ride

[gasman]

Specialized Armadillo Elites
It's all I commute on- I use 25s and never flat. Well except the time a16 penny nail went through the tire and tube.
Ride is harsh but never worry about glass or any other road debris.

[Lovetoclimb]

I use vittoria paves in 24mm on wide rims (Velocity A23 and Hplus Son Archetype) for all of the worst gravel and dirt in my life. Never had a flat or any other issue. Of course I do my best to avoid the worst potholes and large rocks, but have managed to hit some bad ones before. So far so good. Usually running 90/100 front/rear or somewhere in that area.