Tyre pressure / Manufacturers guidelines.
Submitted: Friday, Nov 27, 2009 at 07:35
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Member - Lionel A (WA)
Morning all,
It's been 35 years since I worked for Dunlop as a fitter and lucky enough to also spend time with the R&D / Competion arm of the company.
Even back then, excessive heat was recognised as a tyres worst enemy and low pressures generaly the cause. Hence, the company frowned on any form of pressure reduction.
Today, read any 4x4 mag,
forum, TV show and even 4x4 training, all recomend tyre pressure reduction in various situations.
With the ever increasing popularity of 4x4's, the wide variety of off-road tyres and Manufacturers being aware that most of us fiddle with tyre pressures, just wondering what their attitude is these days.
Cheers......Lionel.
Reply By: Mr Pointyhead - Friday, Nov 27, 2009 at 08:19
Friday, Nov 27, 2009 at 08:19
Some tyre distributors such as Coopers and Procomp also recommend it these days.
Tyre technology has moved on a lot over the last 35 years ....
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Follow Up By: Fab72 - Friday, Nov 27, 2009 at 12:47
Friday, Nov 27, 2009 at 12:47
"Tyre technology has moved on a lot over the last 35 years .... "
Not wrong there. I was watching an old DVD recently of Jack Absalom driving up the
Birdsville Track. He spent a lot of time lecturing about the need to increase tyre pressures to reduce sidewall buldging and hence keep the sidewalls away from the sharp gibbers.
However, the general consensus these days is reduce the tyre pressures slightly so the tyres don't act like over inflated baloons (easy to pop) and reduce the speed accordingly.
I'm heading up that way next year on Highway tyres so I guess I'll soon find out...hopefully not the hard way.
As much as I have researched this topic, although the trend with A/T's is to lower the pressure, when talking Highway Tyres, everyone seems to have an opinion. I wish it was a bit more black and white.
Fab.
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Reply By: Member - Stephen L (Clare SA) - Friday, Nov 27, 2009 at 08:52
Friday, Nov 27, 2009 at 08:52
Hi Lionel
Like above, the tyre industry has come a very long way in 35 years. It also must be noted that when we drop our tyre pressures, so comes down the speed. You only have to read the tyre booklet put out by Cooper, and they recommend various pressure drops for different terrain.
Cheers
Stephen
AnswerID:
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Follow Up By: signman - Friday, Nov 27, 2009 at 09:38
Friday, Nov 27, 2009 at 09:38
Agree Stephen..
It ain't the reduced pressure that causes heat build up/damage !!
It's high(er) speed with the lower pressures....
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Reply By: Peter_n_Margaret - Friday, Nov 27, 2009 at 10:57
Friday, Nov 27, 2009 at 10:57
I use a Michelin road tyre (XDE2) for serious off-road work very successfully.
Michelin publish full pressure/load data for that tyre for "Highway" (max 130kph), "Tracks" (max 65kph) and "Sand" (max 20kph).
The "Sand" pressures are 53% lower than the "Highway" pressures for the same load.
They also quote the "Ground contact area" for those pressures.
This sort of information is sometimes hard to get, but good manufacturers have it. I follow Michelin's pressure recommendations religiously, I reckon they do know something about tyres!
Cheers,
Peter
OKA196 Motorhome
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Follow Up By:- Friday, Nov 27, 2009 at 18:54
Friday, Nov 27, 2009 at 18:54
Peter_n_Margaret, I agree with your approach. I havn't had the misfortune, though I believe there is the possibility of spinning the rims inside the tyres if you try to travel too fast on sand with low tyre pressures. Happy Days. Pauper.
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Reply By: Member - George (WA) - Friday, Nov 27, 2009 at 18:55
Friday, Nov 27, 2009 at 18:55
Heat build-up in tyres happens with speed. On normal sealed highways I run 40-44psi which helps to minimise heat build up. On gravel roads I tend to lower tyre pressure to around 25-28psi and reduce speed to help reduce heat build-up in the tyres. On soft sand I reduce pressure down to 12-18psi and only drive at around 20-30 km/h. Summary - High tyre pressure, high speed, Low tyre pressure, low speed
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Reply By: Member - Phil G (SA) - Friday, Nov 27, 2009 at 22:43
Friday, Nov 27, 2009 at 22:43
If you fit Tyre pressure and temperature monitors (eg Tyredogs), you can monitor these things and adjust accordingly.
The most interesting observation that some friends and I have made is that the outback corrugations will raise the temperatures a lot above ambient.
But running on bitumen at lower pressures at say 80kph doesn't make a lot of difference.
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Follow Up By: Peter_n_Margaret - Saturday, Nov 28, 2009 at 10:08
Saturday, Nov 28, 2009 at 10:08
Nice idea Phil, but I am not convinced that a devise attached to the outside of a tyre valve could give even a rough idea of the temperature of the tyre wall, and it is the wall that gets hot.
Cheers,
Peter
OKA196 Motorhome
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661008
Follow Up By: Member - Phil G (SA) - Saturday, Nov 28, 2009 at 10:53
Saturday, Nov 28, 2009 at 10:53
Gday Peter,
Yeah but the fact that they read higher on corrugated roads suggests they are measuring more than just ambient temp. And I'd expect the air inside the tyre to be close to the wall temp. It would be interesting to test it some other way, but I think they are still giving me useful information. I've had them read as high as 65 degrees, but that was on a 45 degree day!
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Reply By: Phil and Sue - Saturday, Nov 28, 2009 at 10:42
Saturday, Nov 28, 2009 at 10:42
Met a bloke in Turkey
Creek. He was mumbling about flat tyres. Three in two days!!! Compared tracks and asked me how many flats I had. Me - none. Same roads as us and about the same weight etc. He asked me what pressure I ran. I mentioned 40 on highway to smooth dirt and down to about 25 on gravel and mud etc. He ran 35 all the time.
It took a little time but he said he might get a pump and lower his next trip. Pity he didn't do it before this one. I also suggested with low pressures to keep the speed down and check the tyres for over heating.
Luck Maybe!! But lets face it you can make your own luck.
Still no flats in 12 months all types of terrain.
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