Why dirt bike tires hold around 15 lbs. psi optimum?


5 replies to this topic
  • suppresst

Posted April 28, 2012 - 10:20 AM

#1

Auto tires are typically designed to be inflated to lbs. psi in the mid-to-low 30's.

Bicycle tires typically 45 to 60 or 70 psi.

What is it about the construction of the typical dirt bike tire that it is typically inflated to just 15 lbs psi?

Do all dirt bike tire applications involve a tube?

Why do bicycle tires require a tube & dirt bike tires, but not car or heavy truck tires? Is it because auto and truck rims are strong enough to withstand the pressure, but aluminum dirt bike rims can't? Why don't auto manufacturers reintroduce tubes into aluminum rims to save weight, or wouldn't aluminum casted rims be strong enough to support weight of car (they use alum. alloy now)?

Why is a dent in rim of dirt bike tire important to avoid (from what I've read on this forum) if the rim does not have critical function of containing air pressure like an auto rim? What matter a dented rim?

  • MrBlahh

Posted April 28, 2012 - 10:25 AM

#2

I never inflate mine that high

12psi max on hardpack, most of the time I run 10

  • timmyp8823

Posted April 28, 2012 - 10:33 AM

#3

I never inflate mine that high

12psi max on hardpack, most of the time I run 10

+1. I only inflate mine to 15psi when I am riding in rocky desert conditions,and I only do it to cut down on the possibility of pinch flats. When I get back to the woods I go back to 10 or so. 15psi makes my suspension feel like crap and my bike feel busy. Traction also suffers.

  • DHS_sponsored

Posted April 28, 2012 - 10:39 AM

#4

Auto tires are typically designed to be inflated to lbs. psi in the mid-to-low 30's.

Bicycle tires typically 45 to 60 or 70 psi.

What is it about the construction of the typical dirt bike tire that it is typically inflated to just 15 lbs psi?

Do all dirt bike tire applications involve a tube?

Why do bicycle tires require a tube & dirt bike tires, but not car or heavy truck tires? Is it because auto and truck rims are strong enough to withstand the pressure, but aluminum dirt bike rims can't? Why don't auto manufacturers reintroduce tubes into aluminum rims to save weight, or wouldn't aluminum casted rims be strong enough to support weight of car (they use alum. alloy now)?

Why is a dent in rim of dirt bike tire important to avoid (from what I've read on this forum) if the rim does not have critical function of containing air pressure like an auto rim? What matter a dented rim?


Spokes are hard to seal, so thats off road bikes, and bicycles needing tubes.

Truck wheels will be steel generally, car wheels can be steel, or alloy. Because they dont use spokes, they can hold the pressure as tubeless.

As for pressures, its grip, cars have 4 large ish contact patches, if they ran 15 psi in the tyres, the car would be all over the place, and offer no control, shear weight and loadings.......

Bicycles run high pressures, road cycles anyway, to minimize drag, off road you will use lower pressures, but not MX low because the tyre carcass cannot be so strong, weight.

Dented rims normally mean in-balance, and also could be a weak spot, fancy a rim breaking landing a jump, or being at high speed in the desert?

  • RidgeRunnerX14

Posted April 28, 2012 - 12:03 PM

#5

its just the way they are.. :banghead:

  • 2SiX

Posted April 28, 2012 - 12:16 PM

#6

its just the way they are.. :banghead:


X2! 10-12 for most stuff. A little higher for the rocky stuff.





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