Dakar...real action.
Submitted: Tuesday, Jan 12, 2010 at 17:26
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Member - Oldbaz. NSW.
What a great event this is & the coverage on SBS is superb. I was going to say
4WD event, but that isnt strictly true as some competitors are not . As one of
the minority on this
forum who favour higher tyre pressures, I was pleased to
note the comment from a leading driver that higher pressures had to be run
during the rocky stages. A quick google came up with the advice that cars run from 30 psi on sand to 60 psi on stones. This from BFG who have shod most of the winners for the last 10 years. Momentum is a factor of course, & these blokes have plenty of that. 4WD are not permitted to have auto pressure
adjustment & must choose tyre type at start of rally & not change it. Some
categories can carry two spares, others 4. Tyres are not specials..eg armoured.
Anyway, a great way to experience full on off road racing in a variety of vehicles.
If you havent caught it yet check late afternoons on SBS or pay.....oldbaz.
Reply By: RobertHL. Pine Creek. NT. - Tuesday, Jan 12, 2010 at 17:40
Tuesday, Jan 12, 2010 at 17:40
Oldbaz,i heard on abc radio the other day that VW spending over $100mil for this event & i think the standard Izuzu was out as well.I have not watched it though.
Cheers,
Bob.
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Reply By: Willem - Tuesday, Jan 12, 2010 at 17:42
Tuesday, Jan 12, 2010 at 17:42
Yeah....watch it every evening. Most enjoyable. Saw the comment on the tyre pressures.....thats why they get bogged.....even if you enter the sand at 150kmh and stay on top for a while sooner or later you get slowed down and then bogged. And ofcourse most of these blokes have a back-up crew and spare tyres. When we traverse the stony bits with our overladen 4bies we tend to want to drop tyre pressure to make the ride good and to avoid punctures. Do that at 200kmh and it won't work...lol
Cheers
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Follow Up By: Member - Oldbaz. NSW. - Tuesday, Jan 12, 2010 at 18:00
Tuesday, Jan 12, 2010 at 18:00
That is exactly my point, they run high to avoid punctures, some of us drop pressure hoping to do the same thing.....oldbaz.
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Reply By: Member - Rob S (NSW) - Tuesday, Jan 12, 2010 at 17:45
Tuesday, Jan 12, 2010 at 17:45
Hi Baz
Watch it every night and have to get this typed up before it starts.
Some great scenery and awesome sand dunes.
I noted that last night about the tyre pressure.
These are race conditions and different to us average hacks out on the dirt tracks with a bit more time to adjust tyre pressures.And they don't pay for tyres.
They were having a very hard time in the sand dunes to much air pressure lol
Rob
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Follow Up By: Member - Oldbaz. NSW. - Tuesday, Jan 12, 2010 at 18:12
Tuesday, Jan 12, 2010 at 18:12
Cant agree, Rob, these blokes spend millions on this race & any tyre change
costs them the only thing in this race that counts...time. Cost of tyres isnt a factor
...flat ones take time to change. I dont believe that all the experience of these
crews would result in them running any other pressure, high or low, than that
that gives them the fastest time, ie the least tyre damage. cheers...oldbaz.
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Follow Up By: Member - Rob S (NSW) - Tuesday, Jan 12, 2010 at 18:51
Tuesday, Jan 12, 2010 at 18:51
Baz
agreed they run the pressures to get the best time as i said it's a race.
And they don't pay for tyres.
Willem is spot once they bog down in the sand it's hard to get going.
With a high air pressure.
And on the rocks these vehicles are as light as possible.
With different
suspension set-ups.
Not loaded to the gunnels up to 3 tons with the family, camping gear food, fuel, water etc.
How about the basicly stock TD 200 lancruisers doing very well.
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Follow Up By: Off-track - Wednesday, Jan 13, 2010 at 01:35
Wednesday, Jan 13, 2010 at 01:35
A reasonably light weight Dakar racer hitting rocks at speed would probably not be a lot different to a heavily loaded slower moving 4WD doing same. The heavier mass will see to that. My belief remains to let down tyre pressure only in sand, or maybe rock climbing for grip. Works for me.
Ride may be smoother on rough, rocky tracks with lower pressure but you start to induce sidewall flex which can cause failure through
puncture or overheating. Good
suspension will do wonders.
The question I always ask is do farmers, truck drivers, miners, roo shooters, even family car drivers etc lower their tyre pressure as soon as they get off the black stuff? I only see 4WDrivers with little-used expensive compressors '
airing down' as soon as they see gravel. Amusing really.
Mind you it's all a bit of a balance between surface, weight, pressure and speed.
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Follow Up By: Member - Oldbaz. NSW. - Wednesday, Jan 13, 2010 at 10:51
Wednesday, Jan 13, 2010 at 10:51
Offtrack, I'm with you , I find no benefit to lower pressure on gravel or unsealed roads. Sand is diffrent. If you lower for comfort I think you may be only hiding
existing
suspension problems or are overloaded. But freedom means we can run any pressure we see fit, but you & I wont get much support. I havnt staked one tyre since going to 50 psi on my sprayrig, did one a week at 35 psi or less.
Havent ever had a
puncture in my holiday tug at 40 psi & that includes all the
commonly used outback roads. As you said..works for me. cheers...oldbaz.
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Follow Up By: Member - Rob S (NSW) - Wednesday, Jan 13, 2010 at 16:49
Wednesday, Jan 13, 2010 at 16:49
Hi off track
I find most of the farmers, miners, family car drivers etc and 4wd's. have no idea and don't care about tyre pressure as long as the tyres are pumped up to the recommended pressure for sealed perfect bitumen roads.
I my self won't bother to adjust tyre pressure for farm use and gravel roads.
For short distances.
But if i am travelling for days on gravel roads i will make some adjustments.
As you say to get a good balance.
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Reply By: Member - Oldplodder (QLD) - Tuesday, Jan 12, 2010 at 18:31
Tuesday, Jan 12, 2010 at 18:31
And most of them run 235/85 16 tyres.
245/80/16 on sand and 205/90/16 on rock.
BF Goodrich race tyres
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Follow Up By: Member - Oldplodder (QLD) - Tuesday, Jan 12, 2010 at 18:37
Tuesday, Jan 12, 2010 at 18:37
Technical page suggests 20 psi (1.4 bar) for sand and 32 psi (2.3bar) for hard surfaces.
Minimum pressure for sand is 12 psi (0.8bar ) but reinflate ASAP.
rally raid tyre techinical page
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Reply By: Crackles - Tuesday, Jan 12, 2010 at 19:36
Tuesday, Jan 12, 2010 at 19:36
Baz you've overlooked one critical point when comparing racing pressures with those of us who tour. Their speed!
They simply couldn't run a tyre at 25 PSI over rocks to minimise puctures then run at 150 KPH+ all day. It would either bottom out & smash the rim or overheat the tyre & shred it to pieces.
Same on the sand. They use their massive power to weight ratio to get over with higher pressures than what we would normally use touring, simply as they'd pop a tyre off every 2nd time they jumped over a dune if they let them down to 15.
Surely you're not suggesting we run 60 psi for the
Oodnadatta track & 30 psi for the Simpson on a touring vehicle just because BFG recommend those pressures on race cars that top 200 kph??? ;-)
Cheers Craig............
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Follow Up By: Member - Oldbaz. NSW. - Wednesday, Jan 13, 2010 at 11:30
Wednesday, Jan 13, 2010 at 11:30
G'day Craig, I cant see where I suggested anything of the kind, nor did I say BFG recomends any pressure. The site says Dakar 4WD are using those pressures as
a result of the teams experience in such events. I tried to make the point that
Dakar entrants obviously have less downtime with higher pressures, that is...less tyre damage. MMMmm...60 psi is a tad high for the Ood, but I wont be coming
under 40..:)))...cheers...oldbaz.
Ps. I dont get as many incoming rounds as I used to when promoting higher
pressures, think I have won a few over...:))). or are they just bored with it all ??
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Follow Up By: Crackles - Wednesday, Jan 13, 2010 at 20:45
Wednesday, Jan 13, 2010 at 20:45
Can't have it both ways Baz. You quote from the BFG site to back up your theory that higher pressures result in less punctures & now you contradict yourself by lowering their recommended 60 PSI for rock down to 40!
You do seem to ignore the overwhelming evidence & examples given over the years like this
Tyre pressure guide People that see thousands of punctures a year would probably know better than you & I ;-)
Without exception, those that have chosen not to reduce tyre pressures on my outback trips have always had a far greater number of punctures & struggled in the sand.
Cheers Craig...........
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Reply By: Robin Miller - Wednesday, Jan 13, 2010 at 07:58
Wednesday, Jan 13, 2010 at 07:58
But Baz, did you see how much time Robbie
Gordon lost due to an inability to change his tyre pressures when his system failed - may cost him the race.
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