Dr1v3n

Going to ask a tl;dr question and then an extended question

Tl;Dr question - If I want the most traction possible on a gravel bike for the harshest off-road conditions, what kind of tire do I need?

Extra info:
I tend to take my gravel bike on quite aggressive "gravel" rides and I notice that I tend to have serious traction issues when I roll through deeper sand parts of the trail, but more importantly, when descending on loose gravel, sand, and rocks. I basically have to ride the brakse the entire time because if I don't and I pick up speed too fast on a descent I won't be able to stop when I need to. Note that I have a Giant Revolt and the manufacturer says this about my bike:

So, thankfully, I can put a pretty decent sized tire on there. Currently I have a 38c version of this that I run 35-45psi when I am on trails, depending on the trail: https://www.giant-bicycles.com/us/cr...mber=340000222

I do appreciate that these tires do decently well on road, but I am looking at moving to an area where I will virtually use my gravel bike for 80-90% off-road and probably only 10-20% on road, and use my road bike for any of my road needs, so having a pretty intense tire doesn't bother me if it enhances my traction on the trails. Thanks for your recommendations!

My non-tl;dr question would be: "How do rubber compound, tread pattern, and width affect off-road traction?"

Rolla

First, I'd argue that width is just as important as tread. A wide tire tends to float on top of loose surfaces (like sand) instead of knifing in, so if your bike will handle a 45c, that's what I would get.

Tread is important, too, but finding a good one for your specific conditions often takes a little trial-and-error. A good starting point would be to ask at the local shops what tires people in the area are using.

Something like a Maxxis Rambler (700 x 45) or a WTB Raddler (700 x 44) might be worth considering, but there are lots more out there.

The other factor is tire pressure. If your rims are tubeless ready, go ahead and make the conversion when you get new tires. Running lower pressure increases both traction and comfort.

dwmckee

(1) If you are in really loose stuff go 650b and at least 45+ width at 25 - 35 PSI depending on your weight. A few PSI lower an make a huge difference. Take some time to figure out the lowest PSI you can ride first then maybe come up just a few PSI for most rides. It is very common for riders to think they are at low enough pressure, but they really should go lower.
(2) Technique means a lot for fast decent control. Shifting your weight back to lighten up the front tire on a decent can make a huge difference in handling and control.
(3) A gravel suspension fork such as the Lauf makes a huge improvement for decent control when riding fast loose lumpy gravel. It responds quickly to bumps and helps maintain more consistent tire downward force/contact with the surface to prevent front tire loss of traction. (A non-suspension front end tends to have a lot of varying high/low pressure contact cycles on a fast descent and at the low pressure times is when a front skid can start. Suspension greatly evens out the contact pressure and significantly enhances front control.)
(4) There is not one best tire for traction in all conditions, they are optimized for hardpack, sand, mud, etc.

rosefarts

I have Ramblers. They’re ok but are basically wide road tires.

Gravelking SK in as wide as the bike can fit ( more than the manufacturer says in dry weather) is much more like what you want.

rumrunn6

maybe it's time to get a mountain bike w/ 2.25" tires

Dr1v3n

How about https://www.wtb.com/products/raddler ? Heard anything about them? I did also see that those Gravel king SKs are good, but I think they come in max 43 or 44 rather than 45 (I could be wrong). I dont see many comparisons yet, the Raddler must be new... I do see people having air leak issues but otherwise these look like they may be the next best thing besides the WTB Rangers which I think are too large for my bike.

Ha I knew someone may suggest it; I will probably try one eventually, but most MTBers I see focus on downhill whereas I really like climbing and more importantly, I really enjoy the road-bike style handlebars because they keep my wrists in a more neutral position most the time.

Herzlos

I think the basics are that on rough/loose surfaces you want rough/knobbly tires, with enough clearance between them to avoid stuff getting stuck. Look at the agressive MTB stuff like the Maxxis Minion DHB/DHF.
For the road, you want a smooth tire for better traction, whereas the Crosscut's have a mix of both.

You might struggle with the width since 45mm is about 1.77", but it might be worth looking at fitting 29" MTB tyres instead of 700c gravel tyres (as I understand it, they are the same bead diameter).

mstateglfr 

Widest tire with noticeable tread.

My gravel bike has GravelKing SS tires which are semi-slick, but really are basically slicks in the middle. They are 43mm wide and work perfectly for where and how I ride- which are gravel roads. If I were riding sand, rocks, and a lot of loose gravel, I would want the widest tire possible to help float over the surface, and the more treaded tire possible to help dig into loose stuff and gain traction. Tread doesnt do much good on loose deep gravel as it cant get down to the hardpack thats needed to lock on and give traction, but tread does help in sand and loose gravel where the tire can connect with hardpack underneat the loose top layer.

Maxxis Rambler 45
Donnelley EMP 45
WTB Raddler 44
WTB Riddler 45

^ some suggestions to look at in that size. If you go the WTB route, perhaps look into their protection guard tech. Its called SG2 or something similar. Their regular line of tires are notorious for being as air tight as a sponge, and the protection guard tech supposedly solved that issue and also strengthened the sidewalls which is another complaint about the regular line.

chas58

Being the contrarian. ;-)

its mostly technique. very smooth cadence clipless, smooth inputs, fluid soft body movements. Decades ago I used to race MTB on slicks (not knowing any better). Of course, none of that makes any difference is you don't have proper flotation (size) and tire pressure.

Bicycle Quarterly argues that tread is irrelevant on Gravel - or more specifically that if tread doesn't leave an indentation on the ground (think mud), it isn't doing you any good. While I think their use cases are pretty limited, there is some food for though there.

That and what everyone above said. :-)

Chilepines

Rene Herse has done a lot of experimenting with what works and what is myth with tires (I am not promoting their tires!). In their testing supple casing and low pressure are key. No question running a lower pressure will improve traction on the same tire - until it gets too low and it flats!

https://www.renehersecycles.com/tech-info/tires/

rumrunn6

can't go down unless you go up ... it's just that watching MTB videos is more fun when the riders are going down. I use bar ends for some help w/ the wrists. proof about boring climb videos ... lol my nemesis hill 3 times, on 1 ride. the last climb after dark. preserved for when I'm old & grey & can't climb it anymore

unterhausen

I have always wondered about how useful aggressive tread patterns are on gravel. I think that traction on gravel is a function of how well the gravel stays in place. So my thought is that the bigger the contact patch, the less force there is to move any given piece of gravel.

autonomy

My 0.02:
1. You are very unlikely to tell the difference between 43mm and 45mm tires (e.g. GravelKings). BTW, GravelKing SK Plus comes in MTB size of 2" (50mm) - 29 and 700c are the same.
2. Knobs will help you in muddy/leafy terrain but will not on large, loose gravel (they have nothing to grab onto!). You want the widest, lowest-pressure tire to for the biggest contact patch you can get to float over the stuff instead of digging into it.

chas58

that is a good way to look at it.

I don't always agree with Bicycle Quarterly, but they do make a good case for suspension loss.

If I run over rumble strips with high pressure, my bike is going to slow down pretty fast. If I have big enough tires at low enough pressure, the (vertical) vibrations will go away and I'll roll down at the same pace on smooth or rough road surfaces.

and more to your point, yes - if my tire can wrap itself around the gravel with minimal disturbance to the gravel (well, to some degree), I'm going to slide less than if I have a hard tire that tries to ride on top of every piece of gravel, its going to push the gravel out of the way and I'll lose traction.

Darth Lefty 

You can probably guess that softer, wider, knobbier tires have more traction and are not as fast.

Mountain bike tires very often have much different side knobs than the middle. The side knobs are taller and sharper but do not engage unless the bike is leaned over, for a definite change in feel. Brands usually have a progression of tread sizes, but can cloud it up with names and repetitive marketing jargon, the only brand I can think of that doesn't is Trek/Bontrager where bigger number = bigger tread.

It's also very common to run a softer, wider, knobbier tire on the front and a faster, harder wearing tire on the rear. Some tires are designed and marketed specifically for this, or some are marked with different tread directions for front or rear installation. They also sometimes have special tread features like the direction of ramps to the middle lugs that emphasize braking on the front and pedaling on the rear.

The Minion DHF and DHR2 combo is an example.

My Stormchaser came with some semi-knobby tires, Teravail somethings. They look just like the Giant tire you linked. They were fine. When the rear wore out I replaced it with the Gravelking that has side ribs, file tread, and some armor. The front when it wears out is going to get the Gravelking with knobs, maybe in the next size up.

Bingod

If you don't feel confident with your grip then the tire technology and tread design etc wont make much if any difference to your overall speed - you are going to ride slowly and cautiously. I agree, its surprising how much a good tire with little or worn tread can grip even in loose conditions, especially when you are familiar with the trail, but it can be awfully painful and expensive learning what and where the limits are. If like mine the grip levels of your trails are changeable and inconsistent then whose to say what the perfect tire is anyway. I say get a wide, treaded tire with low pressures - you will wear out the center tread soon enough and then you can gauge whether you ever needed it. Good luck

mstateglfr 

I saw one of these at a gravel race a couple weeks ago. Really sharp looking- solid color choice.

Dr1v3n

Thanks for everyone's tips. Due to availability and other reasons, I ended up going with the WTB Raddlers and I went down some of the same trails I had in the past, as well as even harder trails, and I can seriously say that my issue is completely resolved now, running those (700x44C) at I think 35psi worked very well for me. I never slid through anything like I did before. I tested them on mud, beach-type sand, clay-type sand, loose gravel, loose rocks, hard-packed gravel, pavement, etc... (I'm in California so all of that is within a 20 mile radius lol) and they do well. In fact, I even tested them in some of these conditions on very steep grades (35%+) and STILL the traction didn't break even on the rocks. In fact, the grade was so steep that I had to throw most of my weight over the front bars in the lowest gear, to prevent the front wheel from popping up and me falling down backwards, and my legs physically could not go it any more and I had to hop off, and that's never even happened so far to me so the tires I think are all I could ask for for my usages.

Some people have had issues with those tires not sitting properly on their rims and/or other air leak issues, and I've not had such issues so far.

Btw, I found a really nice article on tires during my research for this that I wanted to leave for anyone else wondering: https://www.sheldonbrown.com/tires.html

These are the type of articles from the old Internet/Web that I really miss. No flashy stuff, no crazy sales agendas, just straight quality info!

tyrion

I don't know how much you weigh, but you might experiment with even lower pressure.

afm199

I went from 33's to 40's with a more aggressive tread and the downhills suddenly became infinitely more controllable. As I live on flatlands and ride in the hills, I run 70 psi on the outward and upward journey and bump down to 35-45 psi on the downward. The 33's just didn't put enough rubber on the ground under any rough downhill condition.

Badger6

They matter...also, tires with a higher Threads Per Inch (tpi) count will almost always perform better than a lower tpi count tire. The higher tpi will give a carcass that is more supple and will conform better to the surface than a low tpi tire, and often can be ridden faster and with better traction.

Bingod

Those look like a very good choice. If you can, please post the width of the tyre (tread to tread) on the rim - I've been considering one of those as a front tire because of the bigger side knobs compared to my Resolutes, but would hate to give up width - Thanks