Running low pressures for tubeless

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Running low pressures for tubeless
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flag thegb1212
O+
Posted: Oct 15, 2018 at 21:53 Quote
I have a 30mm inner width rim and 2.4 EXO casing WT tires mounted up tubeless. If I even think about lower than 27psi my tires will start to fold over and squirm all over the place. I am not burping at those pressures, but the squirm is not confidence inspiring. I am also only 165lb.

It doesn't make sense to me how folks can run pressures in the low 20s with a 'standard' tubeless set up. I am talking about non-fatbike, no '+', just plain old 2.2-2.6" tires.

So tell me, how can RC comfortably run 24/22 psi on 2.3" in this review? What am I missing? Don't get me wrong, I love the minimal flats, lower weight, and less fuss I have had with tubeless, but lower pressures aren't one benefit that I have found is possible.

https://www.pinkbike.com/u/RichardCunningham/blog/review-polygon-siskiu-t8.html
"I set the tire pressures at 24psi in the rear and 22 up front and never changed those numbers."

Or here 22/20 psi with 2.6"?
https://www.pinkbike.com/u/RichardCunningham/blog/review-schwalbe-hans-dampf-ii.html
"Aired up to 22 psi (R) and 20 psi (F)"
flag BarneyStinson
Posted: Oct 16, 2018 at 0:24 Quote
How much does he weigh?

My buddy rides super low pressures, but he also weighs less than a sparrows fart.
flag fielonator
Posted: Oct 16, 2018 at 1:31 Quote
I'm 13 stone and run 15psi front, 20 rear. It's fine. 29mm internal rims, stans flow mk3, and 2.5" / 2.4" non dh tyres. I'm not the most agro rider, but i do my best and haven't felt any squirm.

Have you checked your gauge is accurate?
flag huw169
Posted: Oct 16, 2018 at 4:39 Quote
is not a good idea!

(Thought it was a 'finish this sentence' type thing....)
flag Shane-C
Posted: Oct 16, 2018 at 5:10 Quote
Could it be the WT tires? I was under the impression those were best suited for 35mm internal width rims. Have you run a non WT tire with the same issue? Reason I ask is, I was running a 2.6 minion DHf in front and a 2.4 high roller in back on 23mm rims (both tires standard not WT) running 24 psi rear and 22 psi front. Tires would roll over and squirm on rocks and roots and roll over in corners. I just switched to Flow S1 wheels with a 29 mm internal width. Keeping the same pressures the squirming is gone. Maybe try a non WT tire if you haven't, as I believe most of those are designed around a 26-30mm rim, or a wider wheel. Also I'm 6' 4" and 230 pounds.
flag undescended
Posted: Oct 16, 2018 at 9:29 Quote
The wider rim and increased volume SHOULD provide the stable platform to run lower pressure with no squirm or fold. At 11 Stone(155lb) I run 17/20 for 2.4 WT DHRIIs on 30mm rims for all around and increase 3psi for bike park. Can’t say why it ain’t working for you, 1212
flag gbeaks33
Posted: Oct 16, 2018 at 12:36 Quote
I've also wondered this, myself. I get the vibe that having lower pressures is a "cool" thing to do, and I think there's some level of lying or exaggerating when it comes to telling people what their tire pressures are. Being able to get away with a psi of 21 while not rolling, burping, and damaging your rims suggests that you have a perfect (i.e. expensive) tire/rim combo and are a good rider with excellent handling skills to navigate tough rock sections and such. A psi of 30 sounds lame and means you might suck and need extra air to protect your rims from all the jumps you case.

I, for one, don't believe a lot of people when they say what pressure they get away with. I'm sure there's some level of bullshit in there for a lot of people.

I'm >200 lbs and I do 26 in the front and 29 in the rear. Anything less than that and I'm all over the place. I'm also not an amazingly skilled rider, though. So I could see someone who weighs less with low 20s in the front and mid 20s in the rear. But 20? Get outta here.
flag gnarnaimo
O+ FL
Posted: Oct 16, 2018 at 12:53 Quote
gbeaks33 wrote:
I've also wondered this, myself. I get the vibe that having lower pressures is a "cool" thing to do, and I think there's some level of lying or exaggerating when it comes to telling people what their tire pressures are. Being able to get away with a psi of 21 while not rolling, burping, and damaging your rims suggests that you have a perfect (i.e. expensive) tire/rim combo and are a good rider with excellent handling skills to navigate tough rock sections and such. A psi of 30 sounds lame and means you might suck and need extra air to protect your rims from all the jumps you case.

I, for one, don't believe a lot of people when they say what pressure they get away with. I'm sure there's some level of bullshit in there for a lot of people.

I'm >200 lbs and I do 26 in the front and 29 in the rear. Anything less than that and I'm all over the place. I'm also not an amazingly skilled rider, though. So I could see someone who weighs less with low 20s in the front and mid 20s in the rear. But 20? Get outta here.

I used to run sub 20's on my 2.35 dhf/dhr exos in the winter and never burped and it didn't feel squirmy. This was on stock crappy giant am-2 rims. I only weigh 145 lbs mind you...

These days I'm running 2.5 dhfs, with cushcores front and rear at 20-23 psi front and 25-28 psi because I dented so many wheels running stupidly low pressures haha. Never burped or felt excess squirming underneath me however.
flag undescended
Posted: Oct 16, 2018 at 18:23 Quote
There are many articles recently that hit on the benefits of wider rims and increase volume but this one, What tire pressure should you run?, sums it up fairly well stressing how these 5 factors influence your individual ideal tire pressure.

Tire Size and Type
Rim Width and Diameter
Rider Weight
Terrain
Ride Style
flag islandforlife
Posted: Oct 16, 2018 at 21:01 Quote
How are you measuring your pressure? I ask because I just bought a new digital pressure gauge and realized my floor pump is 10 psi off!! So I was having the same questions as you until I found out I was running like 15 f*cking psi.
flag titaniumtit
Posted: Oct 17, 2018 at 4:15 Quote
Depends again on tyre and how supportive the carcass and sidewall is in terms of not squirming under loads.

I would say that using a digi pressure gauge a few times to allow you to become accustomed to seeing the consistency of your tyre pressures and the reading before each ride.

I run 17.5 front and 19 rear but then again I am on 35mm inner width, 2.8” tyres and am a good chunk heavier whilst still running tubeless.

Try googling a pressure calculator somewhere online as there is a rough formula to tyre pressures for the info which you gave us.
flag natas2125
Posted: Oct 17, 2018 at 9:44 Quote
I'm running 26-28psi, but that's just me.
flag PapaGordo
Posted: Oct 17, 2018 at 13:08 Quote
I measure tire pressure using the topeak digital pressure gauge. I also have an analog accu-gauge from GH Meiser for pressures lower than 15 psi. I've been thinking about getting the 30psi accu-gauge to compare to the digital gauge. Depending on the floor pump I'm using, the pump gauge can be as much as 10 psi different from the digital gauge.

I am 200lbs geared up. On my 27.5 bike I run 26psi (f) / 28psi (r) with FTD inserts. Tires are DD casing DHF WT / Aggressor 2.3 and rims are 28mm IW. Without FTD inserts I run 28psi (F) / 30 psi (r).

On my 29er, I run 23psi (f) / 25psi (r) with CushCore. Tires are Goodyear Newton ST 2.4 front and Newton 2.4 rear with the EN casing (1.5 ply). Rims are 31.6mm IW.

I could probably go lower in the front but in the rear I feel like I'm at the lower limit. If I go to the bike park, I do add 2 to 3 psi.
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