Tire pressure....
- Thread starter stosh
- Start date
it would really rely on what you are hoping to get out of your wheel as far as a response.
The pressure, and ONLY the pressure in the wheel affects the size of the contact patch, (all you guys with 3" tires, have to understand that no matter what size tire you have the amount of tire on the ground is the same when you run the same pressure),
The higher pressure reduces the size of the contact patch, and thereby reduces the roling resistance....but also proportionally reduces the maximum avail. traction.
So it is always a compromise..
I say experiment with diff pressures and find a pressure that best suits your riding and makes you feel most comfortable on your bike.
good luck.
The pressure, and ONLY the pressure in the wheel affects the size of the contact patch, (all you guys with 3" tires, have to understand that no matter what size tire you have the amount of tire on the ground is the same when you run the same pressure),
The higher pressure reduces the size of the contact patch, and thereby reduces the roling resistance....but also proportionally reduces the maximum avail. traction.
So it is always a compromise..
I say experiment with diff pressures and find a pressure that best suits your riding and makes you feel most comfortable on your bike.
good luck.
someone once told me to run the lowest pressure I could, without pinch flatting. don't remember why. that's all. Did it help? lol
Are you racing?
just asking, because if you are there are other considerations regarding tire pressures..esp. if you are DHing.
If it is just for daily riding, hucking etc, then just experiment with pressures until you fine one you like, you may also like to run a lower front pressure as usually people impart lower forces on the front of their bikes than the rear during landings, (unless you case something).
having a lower front pressure gives you a larger footprint, and may provide the increase in traction and control to make your landings feel more confidence inspiring.
To a point.. a very low pressure in a large tire may result in a "washy" feeling in the front.
One other thing to keep in mind.
equal pressures in different volume tires, though the contact patch is the same, will have dramatically different appearance concerning the amount of sidewall "squat".
A larger tire requires a lower pressure to "stand", as pressure acts equally on all areas inside the tire, so the greater total surface area results in a larger total force..
(this is why you will not find a large tire allowing very high pressures)
High pressures on a large tire will force it off the rim, and exceed the carcass' ability to stay together.
just asking, because if you are there are other considerations regarding tire pressures..esp. if you are DHing.
If it is just for daily riding, hucking etc, then just experiment with pressures until you fine one you like, you may also like to run a lower front pressure as usually people impart lower forces on the front of their bikes than the rear during landings, (unless you case something).
having a lower front pressure gives you a larger footprint, and may provide the increase in traction and control to make your landings feel more confidence inspiring.
To a point.. a very low pressure in a large tire may result in a "washy" feeling in the front.
One other thing to keep in mind.
equal pressures in different volume tires, though the contact patch is the same, will have dramatically different appearance concerning the amount of sidewall "squat".
A larger tire requires a lower pressure to "stand", as pressure acts equally on all areas inside the tire, so the greater total surface area results in a larger total force..
(this is why you will not find a large tire allowing very high pressures)
High pressures on a large tire will force it off the rim, and exceed the carcass' ability to stay together.
I also run mine 45-50psi. Never had a flat either.
not only that, but larger volume tires, feel softer at a given pressure because they ramp up slower than a skinny tire at that pressure. And a skinny tire at the same pressure will bottom out sooner than a fat tire.
At 140 #s I use about 25 to 30 psi in 2.1-3. 35 -40 in a 1.8 and 5 psi more in a race. I usually run about 5 psi less in the front too.
At 140 #s I use about 25 to 30 psi in 2.1-3. 35 -40 in a 1.8 and 5 psi more in a race. I usually run about 5 psi less in the front too.
Yo STAN,
It's also important to consider the type of tires you're running. You say you normally run @ 35 psi but that it feels a little low for your fat ass. If the tires that you're running have a thin and/or not so stiff sidewall, even though you are running a fairly hard tire pressure it may feel soft. Again, like everyone said, experiment.
I normally run around 30-35 for the uphill sections in dry conditions with a lot of roots and rocks and then deflate the tires by about a third for the downhill sections so my tires will hook up better and cushion the blows. However, if I'm riding in the rain or in wet, muddy conditions, I'll keep the tires around 25 psi so I have a larger contact patch. If I run much lower than that, I risk pinch flatting, rim flattening and tend to roll the sidewalls of the tire when cornering hard which can lead to that 'flat tire' squirrely feeling you get say when you flat a car tire.
It's also important to consider the type of tires you're running. You say you normally run @ 35 psi but that it feels a little low for your fat ass. If the tires that you're running have a thin and/or not so stiff sidewall, even though you are running a fairly hard tire pressure it may feel soft. Again, like everyone said, experiment.
I normally run around 30-35 for the uphill sections in dry conditions with a lot of roots and rocks and then deflate the tires by about a third for the downhill sections so my tires will hook up better and cushion the blows. However, if I'm riding in the rain or in wet, muddy conditions, I'll keep the tires around 25 psi so I have a larger contact patch. If I run much lower than that, I risk pinch flatting, rim flattening and tend to roll the sidewalls of the tire when cornering hard which can lead to that 'flat tire' squirrely feeling you get say when you flat a car tire.
I'm pretty light (120lb) and I run maxxis mobster 2.7's with 36psi rear and 25psi front. i run the back higher cos i dh on a hardtail and so the back washes out first to let me know i'm goin too fast.
i use 55 psi in all riding conditions, just to keep from getting a flat. but i suffer on my ht when it gets rough.
pay's not great but the benefits are fantastic. I have more homemade bungee cordsthan should be legal.
running older WTB 52/54K (I can't remember which raptor off-hand. I think the tyranno) on the FS, and panaracer trailblasters (blazers?) on the hardtail. Even on fatty mcfatfat rims, and 45psi I seem to pinchflat every time I head out. I guess I'm just un-smooth...
Still playing around with tire pressue - I really notice the front tire wanting to skid out if I'm running greater than 40 PSI. Haven't pinched yet at 35.
From all i've read the deal with tires is something like this:
For roadies or trail biking on smooth hardpack high pressure is the way to go because the tire doesn't deform much and you therefore don't have to put any energy into crushing and uncrushing it. It will also track harder, but it's arough ride.
When you start to have a lot of rocks and roots such that you're rarely on smooth ground, a higher pressure tire is actually slower because when you hit a root or a rock, the tire does not deform and your entire bike has to move vertically the height of the object you rolled over. With a lower pressure, the tire eats up some of the obstacle so you spend less time going up and down, and moretime going forward. In real gnarly situations, low pressure is also better because the tire will mold itself a little to the objects you're going over and give you more traction. The problem with this of course is that is you go too low you're going to pinch (that's why tubeless tires are cool)
In mud A lower pressure tire floats on the muck better, this could be better or worse depending on the conditions.
For roadies or trail biking on smooth hardpack high pressure is the way to go because the tire doesn't deform much and you therefore don't have to put any energy into crushing and uncrushing it. It will also track harder, but it's arough ride.
When you start to have a lot of rocks and roots such that you're rarely on smooth ground, a higher pressure tire is actually slower because when you hit a root or a rock, the tire does not deform and your entire bike has to move vertically the height of the object you rolled over. With a lower pressure, the tire eats up some of the obstacle so you spend less time going up and down, and moretime going forward. In real gnarly situations, low pressure is also better because the tire will mold itself a little to the objects you're going over and give you more traction. The problem with this of course is that is you go too low you're going to pinch (that's why tubeless tires are cool)
In mud A lower pressure tire floats on the muck better, this could be better or worse depending on the conditions.