AnswerID: 389996 Submitted: Wednesday, Nov 04, 2009 at 18:03
Member - Duncs
replied:
Bruce,
When it comes to tyre pressures I have a simple formulae that guides, but does not dictate, my tyre pressure choice.
I call it the 25% rule.
I generally start on the highway at around 40psi. When the road turns to dirt I drop the pressure by 25%, that comes out at about 32psi. When the road quality again deteriorates, say turning onto a fire trail I drop by another 25%, I am now down to 24psi. The next step, as I see it is when I go onto soft sand. Once again I drop pressures by 25% that takes me to about 18psi.
Using my system in the high country I would consider that fire trails so I would be running about 24psi
Remember I said this system guides but does not dictate. I would see how it feels and then go up or down depending on how things were going.
It works for me.
Duncs
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| Content with where I am but looking for somwhere else to go. Pic 1 Eric the Emu at home Pic 2 camped on Cooper Cr |
Reply 3 of 4
FollowupID: 657834 Submitted:
Thursday, Nov 05, 2009 at 11:18
Tony posted:
HI Duncs
We are pretty new to
4wdriving, just wondered what type of track conditions you mean by fire trail?
We recently went out in a friends car (prado) to the pipeline track near mundaring,
perth. that was really rocky with big boulders, pit holes and corrgations etc. what would you run the
tyres at for something like that. He didnt lower the tyre pressures.
Cheers
Tony
FollowUp 4 of 7
FollowupID: 657855 Submitted:
Thursday, Nov 05, 2009 at 15:12
Member - Duncs posted:
Tony,
That would fall into my fire trail definition. I developed my system over a few years doing most of my off road work on the east coast near
Sydney. Blue Mountains, Nowra,
Stockton and a the like.
My favourite track was down into Deep Pass, National Parks have closed it now. It used to take me 20 min to walk and 45 to drive. Big steps, funny angles and lots of
sandstone.
I find much under 24psi on that sort of stuff is to soft and you risk breaking a bead. 24 lets the tyre wrap around the rocks etc giving better grip and reducing the risk of punctures.
Duncs
Click Image to Enlarge |
| Content with where I am but looking for somwhere else to go. Pic 1 Eric the Emu at home Pic 2 camped on Cooper Cr |
FollowUp 5 of 7
FollowupID: 657856 Submitted:
Thursday, Nov 05, 2009 at 15:19
Member - Duncs posted:
Should have mentioned, when you drop tyre pressures drop your speed as well.
Remeber you lowered your tyre pressures because the
road conditions dictate that. That should also have an impact on your speed
While at 32psi you can probably travel at highway speeds you certainly can't at 24psi. If you don't slow down the
tyres will overheat and that can cause a whole bunch of other problems.
Duncs
Click Image to Enlarge |
| Content with where I am but looking for somwhere else to go. Pic 1 Eric the Emu at home Pic 2 camped on Cooper Cr |
FollowUp 6 of 7
