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What pressure to run my tires at?

DirtMcGirk

<b>WAY</b> Dumber than N8 (to the power of ten alm
Feb 21, 2008
6,379
1
Oz
I'm trying to get a baseline on what pressure to run my tires on my TR450.

Geax Neuron/DHEA on a mavic 819 running tubless. Got two scoops of Stan's in each just for grins.

Have it up at 40psi, and traction was for ****.

I'm a big man. 240# of DirkManJello.

Thoughts?
 
Traction is a function of compound, psi, terrain conditions, riding style, and suspension setup. I'm assuming you have addressed the others? I run 25-32psi on the rear, 23-25psi on the front. I am 185lbs. I go thru 1-2 rims a season of riding and racing. I also run xc tubes....and probably go thru 4-5 tubes each season.
 

DirtMcGirk

<b>WAY</b> Dumber than N8 (to the power of ten alm
Feb 21, 2008
6,379
1
Oz
See, I've never gone through a rim running 35+

I gave up on tubes years back. They didn't work in VA, and it doesn't work in Phoenix.
 

Transcend

My Nuts Are Flat
Apr 18, 2002
18,040
3
Towing the party line.
You guys run insanely high tire pressure. Most racers on specialized/maxxis Dh tires are running between 23-26 PSI. The higher usually 2-2.5 PSI higher in the rear.
 
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ustemuf

Monkey
Apr 8, 2010
198
15
Bay Area
i run ~26-28 in front, ~28-30 in rear. tubeless on maxxis dual ply.

i use 40psi when i am trying to set the bead :rofl:
 

samnation

Monkey
Jan 25, 2009
139
0
Somewhere in KANURDUR
For a long time I was 18psi front 21psi rear now after some flat issues I am 23 front and rear. As a baseline given your weight and where you are coming from I would say between 25 and 30 just to get used to the low pressure.
 

b.utters

Monkey
Mar 30, 2011
135
0
^ahahahahaha

23-25 front 27-30 out back depends on the track though. Most tracks I ride are hard packed and dusty as ****.

If it gets supper dusty or sandy drop the front down t0 18 and the rear to 23.
 

Mo(n)arch

Turbo Monkey
Dec 27, 2010
4,441
1,422
Italy/south Tyrol
I'm running 1,6-1,8 bar (24-26psi) in the front and 2-2,4bar (29-34psi) in the back. Anything more in the front results in washouts and all around less grip.
I am at 90kg (198lb) in full riding gear.

You guys run insanely high tire pressure. Most racers on specialized/maxxis Dh tires are running between 23-26 PSI. The higher usually 2-2.5 PSI higher in the rear.
Are these the pressures ridden by the pros? I thought, they had much more in their tires...
 

norbar

KESSLER PROBLEM. Just cause
Jun 7, 2007
11,346
1,587
Warsaw :/
That's high. I run 23-25psi, a bit more if the track is slower and I want to roll faster. 40psi even if you're heavy is a lot.



Fraser - I second the question above. Always thought they went with higher pressure for better rolling.
 

vikingboy

Monkey
Dec 15, 2009
212
2
FWIW: Im 95kg, run easton havoc rims (cant recall width, sorry) and tubeless Specialized Hillbillys at 23psi front, 27psi rear.
I found much lower and the sidewall flex started to make handling suffer. Much higher and traction fell off.
I spent quite a bit of time messing with this over a range from 18psi to 40psi front and rear.
 
most of the WC racers run tubed in the back because they burp or can blow off a bead of a tire with the speed they are carrying in the corners or thru the chattery stuff.

it has always been my opinion, that by the time you buy an UST specific rim (which is typically alittle heavier than non-UST specific counterparts), rim strips, valve, sealant, and UST specific tire, you don't really save that much weight...maybe 50-100grams at most per wheel. i like my tubed setup because i can change tires easily don't have to worry about setting bead with a compressor (in some cases) and messiness with sealant.

and i'd rather have lower pressures for optimum traction than run higher pressures for rolling resistance.
 

norbar

KESSLER PROBLEM. Just cause
Jun 7, 2007
11,346
1,587
Warsaw :/
most of the WC racers run tubed in the back because they burp or can blow off a bead of a tire with the speed they are carrying in the corners or thru the chattery stuff.

it has always been my opinion, that by the time you buy an UST specific rim (which is typically alittle heavier than non-UST specific counterparts), rim strips, valve, sealant, and UST specific tire, you don't really save that much weight...maybe 50-100grams at most per wheel. i like my tubed setup because i can change tires easily don't have to worry about setting bead with a compressor (in some cases) and messiness with sealant.

and i'd rather have lower pressures for optimum traction than run higher pressures for rolling resistance.
Buy SKF rennenkompressor which contrary to its name is a floor pump and you won't need anything else. It still takes some energy but that pump is awesome. Some roadie friends suggested it to me and surprisingly it works here too.
 

captainspauldin

intrigued by a pole
May 14, 2007
1,263
177
Jersey Shore
I've been running around 35psi in the rear on my dh bike to prevent burping, seems like anytime it goes lower than 35psi I start burping(tubeless, 823s, 3c 2-ply 2.5 dhf). Front I typically run 26-30psi. But I'm also like 230-240lb..
 

9nine9

Chimp
Apr 23, 2007
42
0
28 psi for me. Any lower and it burps every time. I just started around 32 psi and kept dropping till started burping. 180lbs, Mavic Deemax, Minion DHF USTs. For a few years now.
 

Transcend

My Nuts Are Flat
Apr 18, 2002
18,040
3
Towing the party line.
That's high. I run 23-25psi, a bit more if the track is slower and I want to roll faster. 40psi even if you're heavy is a lot.



Fraser - I second the question above. Always thought they went with higher pressure for better rolling.
Nope, usually fairly low. Grip counts for a lot. If they get a flat, they may go up 1-2 PSI. If I remember right, Sam usually has about 23-25 PSI in his tires.
 
Aug 4, 2008
328
4
For me 32-35 PSI front and 32-40PSI rear.

823, 2ply DHF or Muddy Mary. 100kg Rider

Lower pressures cause burpage and rim hittage, the traction seems pretty good. The tubed equivalent would be 25/30 PSI in my experience.

Also I wouldn't trust read too much into what your average WC racer does as they are as prone to cargo cultism as the next guy.
 

Transcend

My Nuts Are Flat
Apr 18, 2002
18,040
3
Towing the party line.
Aren't these the same guys routinely flatting on race runs?
Monster Specialized has had about 1 flat in 3 years on Specialized tires (Last week in Windham - Sam's race run.) I'm not 100% on the pressure but that's within 1 or 2. I know they are fairly low, they even surprised me.

Oddly, last week Minnaar and Bryceland converted to Stans No tubes tubeless for the first time and Greg was loving it. They did it to try and prevent pinch flats on all of windham rocks. It seems that recently, the guys with flats have been mostly on Schwalbe. Probably an odd coincidence and square edged rocks in the race line, but it was noticeable. (Mondraker, Devinci etc.)

Also I wouldn't trust read too much into what your average WC racer does as they are as prone to cargo cultism as the next guy.
As someone mentioned above, the majority of WC guys do not run tubeless because they corner like demons. Even at high pressure, they will burp a rear tire.
 

Huck Banzai

Turbo Monkey
May 8, 2005
2,523
23
Transitory
As low as you can go without rolling the bead and burping.
Start with 25F and 28R and adjust.
I'll go as low as the tires will stay on and not ding off of everything in site. When i ran tubes, i'd find I lowered myself to about 18F 22R -- occasionally even lower, but you really notice the squirm.

With tubeless, if I run the rear under ~35, I *WILL* burp somewhere; maybe I need to mount the tires with a soapy bead and jack the pressure for some set the beadlock action? (and then back down to 'normal' pressure)

Note: I am ~205 (was ~250, yaaay!)
 
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DirtMcGirk

<b>WAY</b> Dumber than N8 (to the power of ten alm
Feb 21, 2008
6,379
1
Oz
I'm going to give 32 front and rear a try Sunday when I go to Northstar.
 

NoUseForAName

Monkey
Mar 26, 2008
481
0
I'm surprised no one has brought up the width of the rim. Your sidewalls would be less floppy at low pressure with a wider rim.
^^ This. You're a big guy and you've got skinny XC rims on your bike. Your tires aren't going to work properly at any pressure.

Ditch the 819s and look for something with a *minimum* 21mm internal width. Better would be 23 or 25mm.
 

certified

Chimp
Aug 31, 2011
14
0
UK
Monster Specialized has had about 1 flat in 3 years on Specialized tires (Last week in Windham - Sam's race run.) I'm not 100% on the pressure but that's within 1 or 2. I know they are fairly low, they even surprised me.

Oddly, last week Minnaar and Bryceland converted to Stans No tubes tubeless for the first time and Greg was loving it. They did it to try and prevent pinch flats on all of windham rocks. It seems that recently, the guys with flats have been mostly on Schwalbe. Probably an odd coincidence and square edged rocks in the race line, but it was noticeable. (Mondraker, Devinci etc.)



As someone mentioned above, the majority of WC guys do not run tubeless because they corner like demons. Even at high pressure, they will burp a rear tire.
Thats interesting the santa cruz boys were doing that, I think there is a disadvantage to the rims, if Steve wasnt running carbon rims maybe he might not of punctured... did you see the state of Gwins rim after his run? he was lucky he didnt puncture.
 

DirtMcGirk

<b>WAY</b> Dumber than N8 (to the power of ten alm
Feb 21, 2008
6,379
1
Oz
^^ This. You're a big guy and you've got skinny XC rims on your bike. Your tires aren't going to work properly at any pressure.

Ditch the 819s and look for something with a *minimum* 21mm internal width. Better would be 23 or 25mm.

Meant to say 823's. Wasn't all here last night.
 

SCARY

Not long enough
I tried for years to ride in the mid 20 range and wasted alot of money going to races and getting flats.I decided to up my tire pressure and soften the initial stroke on my suspension to try and compensate for the lesser traction.Which is why I love the dorado(you can do that and still have stiff suspension)and the VPP of the M9.I also,when at home and not racing, will run 35f and 40 rear ,so when I drop down pressure at races it's not so bad feeling.Plus,in Phoenix it's dust/gravel over rocks so just about anywhere else there's a ton of traction comparatively .I just decided to deal with it and work on my skill level.Plus,I don't have the patience to trash 5-6 rims a year.
190 on 721s(soon,maybe enve's)
 

FCLinder

Turbo Monkey
Mar 6, 2002
4,402
0
Greenville, South Carolina
Most DH tires are designed to be ran at 28psi. The designers will set the knob placement on the tire casing at that psi for maxim grip at all angles on the tire. When running lower PSI say 24 to 26 psi you will not be getting the correct path of contact for the knobs to do there job per design. Same when running higher PSI over 28psi. The tire will no fold or move at the side walls being stiffer due to air volume. Now with all this being said, the difference is at a small amount. But when you only win or lose by .01 of a sec, it all counts. All is info has been told to me by 2 different bicycle tire engineers and for big companies. They also say if your supision is setup right you don't need to play around much with PSI for traction. I have had many long conversations with these guys over the years as I am a tire geek in a way.

A good trick for you guys running Tubes is to make sure to Baby Powder up your Tubes and Tires to allow the tube to move around in the tire. This will help the tire fold and grip better.

I have a TR450 and I am 170lbs. I run tubeless the Continental DeBaron up front and a DeKaser in the rear most of the time. My front PSI is 27psi and the rear set at 28psi. I have complete trust in them at this PSI for Grip and Burp/Fatten resistance. I have only had 1 flat with a tube since being on Continental in the past 2 years. That was because I didn't check my PSI before riding. It was to low.

I don't consider myself a Tire/Suspension Pro, but I have been lucky to have tested a lot of tires and Suspension systems in my time.

Hope this helps out some,
Cecil