[Closed] Tubeless tyres and low pressures ?

I run 20 psi front tad more in rear - bit lower in winter

If you work with imperial numbers, the basic starting point is:

Rider weight in kit (in stones) x 2 = psi Minus 2 psi front and plus 2psi rear

Depends on your trails and the tyres, natural riding and a decently tough tyre will take 20-25 without much issue. Heavy g-outs with embedded rocks that you tend to find at trail centers need a higher pressure to avoid punctures.

^ not seen that equation before but it does seem about right for what I have my tubeless tyres...20-23psi.

Although I do tend to just squeeze my tubeless tyres to determine whether they're at the right pressure, something I never use to do when running tubes as always used a gauge

The equation is from the Stans site.

I run the same pressures tubless as I did when I had tubes, 25psi front and 30 rear, any lower and Id be at risk of dinging the rim, same with tubes, only any lower and I would be risking pinch flats.

In answer to the OP, I don't think you can automatically run lower tyre pressures with a tubeless setup.

Massively dependent on tyre and rim combo but one of the best things I have done to improve my riding this year is check the pressures every ride. Find a suitable pressure and stick with it as variations make a massive difference to handling.
I'm 83kg and ride 23 front 27 rear (Schwalbe MM + RR / HD) which is not too far off the stans equation.

HTH

18psi front 20psi rear on Stans Crest 29er with Nobby Nics.
I'll probably run them a bit lower tbh as they're on a Air9 Carbon with RDO forks.

Just ran my front @ 16 psi for two weeks in morzine. Stans licensed Sun Ringle rims with a non tubeless dual ply minion

Been racing the Scottish enduro series with a chunky monkey at 17 psi this year on a flow ex rim and a wtb non-tubeless rim.

Rear tyres have been ran in the low 20s

I weigh 180lbs

Zero problems running these pressures

I don't understand how a lot of folk are getting away with such low pressures. I used to like less than 30psi in my rear tyre, but have had to increase that after too many dings and pinch punctures (in the tyre). Less of a problem up front, but found the tyre wall creasing/collapsing just above 20psi. I only weigh 65kg too!

Edit: I'd like to know how accurate some folks' pressure gauges are.

28/30 in the front, and a bit more in the back.
Any less and I find the tyres squirm in berms.
I don't get how people can ride with 12 psi in tyres, it might be because I'm a bit fat. 😀

Edit: I'd like to know how accurate some folks' pressure gauges are.

I've got a topeak one which is supposedly very accurate. Plus the tyres feel very soft. Never notice any squirmyness in berms but my riding does tend to be natural, rooty, muddy, rocky stuff

Usually 20-25 for me but it depends on the tyres too- I'm not hard on tyres for whatever reason so I can get away with lighter sidewalls than most, but that tends to mean a little more air because of the lack of support.

. Less of a problem up front, but found the tyre wall creasing/collapsing just above 20psi. I only weigh 65kg too!

what tyre?

24lbs front and rear on 29er Rons
Could almost certainly drop a bit on the front, but I ride in rocky exmoor/dartmoor and am a bit scared to do so!

The Stan's formula quoted above is a good starting point. For a given rider, factors that demand higher pressure are, smaller volume tyres, less stiff sidewalls, narrower rims and smaller diameter wheels. Bigger stiffer tyres on wider rims on bigger wheels allow lower pressures.

For a given bike then a heavier rider needs more pressure (hence the formula) but so too does someone who pumps harder and pulls more G in turns, hammers through the rough harder and lands harder (especially coming in sideways).

In greasier conditions then you can usually run lower pressures without burping, squirming or pinch flats.

Josh Bryceland (11 stone 7) is running 29psi front, 30-31psi rear on 2.4" dual plies on his downhill bike. Jared Graves (13 stone 5) is running 26psi front, 29psi rear on 2.3" reinforced single plies on his enduro bike.

I generally run 20psi up front and 30-35 rear with my hutchy toro's 2.35
I ran nobby nics for 6 months but just couldn't get a hsppy feel from them compared to the toro's, tried them from 15psi front to 30, and 18psi rear to 40, bit wallowy on the low pressures mind,
On tubes i had to run the front at 30-35psi and the rear at close to 50 to avoid pinching. 100kg pre kitted up mind on a hardtail.

d45yth - Member

I don't understand how a lot of folk are getting away with such low pressures.

Most are running low to mid 20s in the front and high 20s, low 30s in the rear apart from boardinbob but he's running Dual plys, sidewall stiffness plays a big part in it, I don't use dual-py but always buy a tyre with tyre wall reinforcement.

AP probably weighs 70kg ish?

On my 26" 140mm hardtail with Flow rims and UST 2.2 Rubber Queens I've found 24psi front, 27psi rear works well. On my 27.5" 160/140mm full-sus with Flow EX rims, Protection 2.2 Trail King rear, Super Gravity 2.35 Magic Mary front, I've ended up down at 18psi front, 23psi rear! I'm about 12.5 stone.

Im guessing the slightly bigger wheels, wider rims and stiffer carcass on the Protection TK vs UST RQ is why I'm running a few psi lower out back on the big bike. The Magic Mary is no bigger in volume than the Trail King but the Super Gravity casing has full dual ply sidewalls and it's much stiffer, hence the even bigger drop in preferred pressure out front.

One of my mates weighs about a stone more than me but really shreds around berms and can't run less than 30psi without risking burping - but he's on skinnier Mavic 26" rims (Protection 2.2 TK tyres) and I don't know if his pump is accurate (my bet is that it's over-reading) - there's no way he's pulling more G than Mr Graves!

I should add that Jared Graves is running quasi-ghetto tubeless to reduce burping - so proper tubeless tyres on tubeless rims plus split BMX tubes as rim strips - I'm guessing he'd need more pressure otherwise. The new Procore system looks great for racers struggling with getting maximum grip without burping or flatting.

Running Conti RQ's tubeless I run them so that the sidewall deforms evenly rather than creasing if I push the bike into the ground at about 45 degrees. I've never got around to taking a pressure reading though - i don't trust track pump guages at low pressures. Have a Topeak digital guage but have only ever used that for the car.

Current front RQ is broke though. New tyre with only a few rides but horribly deformed and needs replacing.

I find if I run less than 25 then I'm at high risk of burps. If a burp results in a completely flat tyre (it usually does) then I have to stick a tube in which inevitably means two or three pinch punctures before the end of the ride. So I always use around 25psi front and 30 rear to make sure I don't burp - ever.

If I could run less pressure without complications (burps, ring dings) then I would for sure. The whole procore thing could change the game.

Hmmm - was thinking of going tubeless, I currently use innertubes at 22psi on the rear (2.5" tyres on 35mm 29er rim) and 7.5psi on the fat front. Now if what people are saying, I may have to increase my pressures, if I went tubeless to avoid burping? :(( that's suboptimal!!!

Normally about 22psi with flow EX rims and mavic Charge / Roam XL

Ard Rock killed my rear tyre tho so had to run the last downhill on 15psi and I had a LOT of grip

New rear probably won't be as strong as roam sidewalls so I'll be keeping it at 22ish. Riding is mostly natural stuff tho and I'm not light - circa 80k

Hmmm - was thinking of going tubeless, I currently use innertubes at 22psi on the rear (2.5" tyres on 35mm 29er rim) and 7.5psi on the fat front. Now if what people are saying, I may have to increase my pressures, if I went tubeless to avoid burping? :(( that's suboptimal!!!

Huge tyres, wide rims and light rider - I can't see you burping anything at those pressures!

Now if what people are saying, I may have to increase my pressures, if I went tubeless to avoid burping? :(( that's suboptimal!!!

I would say it all depends on what you ride and how aggressively. The times I've burped it's either railing a corner really hard and you can feel the tyre rolling off the rim, or from the front wheel half-hitting a 6" ish rock at good speed which obviously causes a twisting of the tyre. Also the rim/tyre combo is crucial and I guess 35mm rims would burp less.

However, despite all of that, I would suggest that if you're safely running 22psi with tubes (without rolling the tyre off, pinching or dinging the rim) then you're obviously a lighter/smoother ride than me and perhaps my experiences don't apply. I think aggressive, heavy, pinch-prone riders have a lot more to gain from tubeless.

Most of my burps come from sliding off the side of a rock - I've managed it climbing. I suppose it's a sudden tug on one section of the tyre. If you're moving quickly the wheel rotation means it can quickly reseat but at slow speed the one section of the tyre is deformed for longer.

Hi Chief - should be back riding in a couple of weeks 🙂 May tubeless the fat front , see how that goes.