Well the answer according to this article is 2.8” tires for pretty much every condition - descending technical terrain, descending smoother terrain, and climbing.
Why doesn’t Nino Schurter rock 2.8” tires on 35mm rims?? 
Interesting tests. Regarding the Pro MTBers, if they could get a free 1-2% bump in speed I’m sure fat tires would be all the rage. There are likely other trade-offs that negate the apparent speed increase.
XC Pro’s have gone up in tire size from 2.0-2.1 a few years back to 2.25-2.35 nowadays. I think Nino runs a 2.30 or 2.35 on 30 mm internal width rims now. Wider tires allow lower psi and better traction. I imagine as the size goes up, so does the weight and the offset doesn’t justify going up to 2.6 or 2.8. Not to mention, the current geometry and bike frames don’t allow for wider tires. I race a Scott Spark with 2.35 tires and there’s not much room to go any wider. I believe the manufacture (Scott) recommendation for max tire size is 2.30 for the Spark.
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But they were really testing 2.3, 2.45, and 2.65 inch tires!
My Bontrager team issue xr2 on 30mm rims measure 2.62, so this has me wondering if actual 2.8s or 3.0 are even faster? In other words, where is the cross over where bigger is too big?
Sometimes I ride my fatbike on the trails with 26x4.8 tires, and I’m amazed how “not slow” it is - it sure is slow on the pavement though with the appropriate trail pressure.
This is what I’m going to be telling myself for 2 hours during Iceman in 2 weeks. Watch out Kabush!
This’ll make me rethink my next bike - May opt for a bike designed for 2.6”, maybe more.
That’s still a few years away yet tho - need to break my current bike first!
But by then, conventional wisdom will probably have changed again!
Yeah, that’s what I like about my Ripley - it’s designed around true 2.6 tires. Once you get used to the bigger rubber, it’s hard to go back to 2.2-2.35.
2.4-2.6 is the way to go
My bike is a 2018 Stumpjumper, and it was available with 29/2.25, and also 27…5/3.0. Mine came as a 29er, but I got a set of the plus wheels and tires, so I can swap them back and forth. I believe they are faster in anything rougher than a coarse gravel road. Since I got the fatter wheels and ties, I don’t see myself using the 29ers much in the future.
Tyre width depends more on the trails you’re going to be tackling. A tyre I would use for XC racing is completely different to one that I would use for enduro.
The sweet spot for XC is 29" in the 2.3ish range.
29" plus tires get a lot heavier.
The BikeRadar video/article is comparing 27.5" wheels, which don’t have the rollover ability of the 29ers.
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Yep - it can be frustrating when you buy a tire with an expected width, and then it turns out to be different. I think tire manufacturers should also provide somewhere the rim width that the tire measurement applies to, or the bead-to-bead casing width.
I recently bought the new bontrager xr4 tires to replace my xr3s. Both supposedly 2.4, but the new ones are about 0.15” narrower than the old ones.
The new bontrager tires are all designed to be run on treks new 30mm rim width wheels. I have older wheels with 24mm width. So while the new tires may be 2.4 on 30mm rims, they are not 2.4 on 24mm rims.
Next time it comes to buying tires, I’ll bring my measuring tape with me to the bike shop and measure bead-to-bead width. And compare that with my current tires to get a get a better idea if the new tires will be narrower or wider than current.
We’re at a point that tire makers should be including the recommended Rim Internal Width range, and the specific width corresponding to the primary tire width spec.
There is so much variation in the tires and wheels now, that it is very easy to get confusing results that are well off the nominal dimensions claimed.
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I think it’s the weight. I don’t think there is any way you’re going to talk top level pros into taking the weight penalty on 35mm rims and 2.8 inch tires. Going from a 25-27mm internal rim and a ~2.35 inch tire, you’re talking 50g per rim minimum, probably closer to 75g. And the tires might be 100g heavier each. The traction is great, but those bikes are so optimized I can’t see anyone volunteering to hang 3-400 g more on there.
I’m resurrecting an old thread vs starting a new one.
Last fall, I put 2.6” tires on my MTB for a bikepacking trip to get a little more float in the sandy sections of the route. I normally ride 2.3-2.4” tires
Being lazy, I left the 2.6” tires on over the winter, and have started my spring trail riding with these bigger tires. I was planning on swapping them out for my smaller tires for a race I’m planning to do later this spring - but after my ride yesterday, I’m thinking of keeping the bigger tires on the bike.
Yesterday, I rode the lunch loops trails in Grand Junction, Colorado. These are desert-style trails - rocky, sandy and technical, with very few smooth sections.
I had the tire pressure at 18 and 17 psi respectively, front and rear, about 2-3 psi lower than my normal sized tires.
I noticed a difference with these tires - not huge, but they did seem to reduce trail chatter, and seemed to have a little better grip vs the smaller tires.
Then I looked at Strava to find a segment where I know each time I rode it I was probably riding as fast as possible - a 0.6 mile fun downhill technical section.
Results below - showing my 2 rides yesterday were the fastest of 6. This is definitely not a scientific study for a bunch of reasons, but the times, combined with my subjective feel of the tires above makes me wonder if these bigger tires are faster on a technical course like this.
Any one have similar experience comparing different tire sizes on MTB? Any conclusions or preferences?
Note: the 2.6” tires are both Bontrager XR4
I usually ride a 2.4” XR4 on front, and a beefier (more puncture resistant) tire on the rear, most recently a 2.4” Schwalbe Wicked Will
Now go and compare your times on the climbs and flat sections of the course then report back here for analysis.
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I don’t have good enough data to do that. Some of those rides were training rides, others races. Uphill very dependent on how hard you are pushing. Downhill a better comparison cause on a fun downhill - well, I’m generally riding as fast as possible all the time!
The data reported in the link at the top of the thread is better than mine. Video of same evaluation here.
The bigger tires (2.8” nominal, but 2.65” measured) were faster descending, lower rolling resistance, and no difference climbing up a steep trail vs 2.3” benchmark.
So you’re saying a heavier DH 2.8” has lower rolling resistance & no different climbing compared to a XC 2.35” tire?
Going DH… sure. Going uphill? Going to need some data to back that up
No. Per the bike radar test, the 2.8” Butcher tire (measured width 2.65”) vs the 2.3” Butcher tire.
There aren’t a lot of tests that I can find measuring performance of different tire widths. The one linked is the best I’ve found, but it’s 5-6 yrs old at this point.
The reason I resurrected this thread is based on my experience yesterday riding 2.6” tires on a chunky technical trail. They felt better - less chatter, better grip - and maybe faster (based on my non-scientific segment time comparison) vs my narrower tires.
Keep in mind that wider tires and lower pressures (than “traditional”) have been shown to be faster for road and gravel, and both disciplines have moved to wider tires over the past few years.
And MTB is already heading in this direction with 2.4” tires on 30mm rims becoming standard for XC. If XC bikes were designed to fit wider than 2.4”, might we see even wider tires on the more technical, rough trails?
Ha - re-reading this post of mine is funny. I did indeed break my old bike and got a new bike that can fit 2.6s.
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