Thread: D2 tyre pressures

40psi for the black top
25psi for bush
16psi for sand
This is what i run on my d1 with 265/75/16 AT2 tyres.

Originally Posted by boofdtl

40psi for the black top
25psi for bush
16psi for sand
This is what i run on my d1 with 265/75/16 AT2 tyres.

The "ideal pressure" for those tyres on a tdi d1 at kerb weight is 26psi front 27psi rear for full street pressure. You are effectively running a street contact patch for off road.

fwiw ....

Standard load/passengers ... not loaded for camping/touring.
Cooper S/T 255*70/16 (passenger construction, not LT)

Road 33/38
Bush 22/24
Beach 15/18
Soft sand/mud 12/14

... with appropriate reductions in speed & right foot application of horsepower.

Remember that the D2 alloy rims have the extra bead retaining ring internally which virtually stops the "rolling" the tyre off the bead issue.

Originally Posted by OffTrack

The "ideal pressure" for those tyres on a tdi d1 at kerb weight is 26psi front 27psi rear for full street pressure. You are effectively running a street contact patch for off road.

So what do you run your tyres on the street and bush and sand??

In the cooper manual (from memory) correct tyre pressure can be obtained by the following method.

For Blacktop (or anything actually but lets work with blacktop first)
1. Record your cold tyre pressure (try manufacturers pressures) - dont drive down to the tyre station to do this- they need to be COLD.
2. Drive with current pressures for 10 minutes or so until the tyre has heated up.
3. Check the tyre pressures again. If they are EXACTLY 4psi higher than when you measured them cold, they are the correct tyre pressures for whatever conditions you are running.

The same principle rings true for sand. For example on an 18 month trip around Australia, in my defender (loaded) I ran:

blacktop

48 rear
32 front (higher than standard but I had a bull bar and winch)

fast dirt

same as road

Slow dirt (heavy corrugations etc)

36 rear
24 front

very slow dirt (off road)

As low as 30 rear
20 front.

For sand

24 ish rear

16-18 front (depending on sand)


Now obviously I had a heap of time on my hands but each of these COLD pressures would increase by exactly 4 psi when the tyres got hot. I thought that was really interesting. But then Im a nerd.

Thats how I read the cooper manual anyway. And after 45'000 kays around this great land (religiously rotating and balancing every 10,000 kms as you should do with a heavy tyre), I got exactly 0 punctures. That's right - not a one. Did the Cape, Gulf country, Outback Qld and NSW, the Birdsville, Flinders, Great Central and a heap of others and no tyre problems at all.

Tyres were the 'dreaded' cooper st's which I thought was poetic.

Pricey.

'EDIT'- now before anyone says this is a defender not a d2, the theory actually works with ANY 4wd. Trying it out on my D2 now (as I sold the defender) and will let you know how the nerdy process goes

I was led to believe pressures on the tyre placard on the D2 give the best ride & handling balance for the OEM tyre Michelin XPC.They are not necessarily the correct pressure to maximise long life from the tyre & don't suit everyone.

Can't remember what i used to run them on,but for the BFG/AT's i run 40psi at all times,dropping to 30/32psi for dirt & corrugations,22 for sand,dropping to 18 or even 16 for the very soft stuff.I keep the pressures the same all round & rotate every 10K.

After 85k,and desert,cape trips,etc,etc,not one puncture.Some of those trips we were very heavily loaded.

As said by gusthedog, (the4 psi thing)is the way to go if you want to get pressures perfect.

The 4 psi test was told to me as the "Pirelli Test" by knowledgable chap (SAS tactical vehicle specialist)

If you get more than 4 psi rise after driving then cold pressure was too low
Less than 4 psi and cold pressure too high.

i.e cold 28 hot 34 then you need to increase cold pressure by 2 psi.

in this situation increase the hot pressure by two psi to 36 check it agian when cold (should be about 30).

with this test on Scorpion ATR I run 2 psi above placard when unloaded and loaded up for a trip is 4 psi above placard for front tyres and 10 psi above placard for rear.

last set of scorpion at's had perfecctly even tread wear across the tyres and I got max use out of them.

for sand its a bit tricky as the 4 psi thing is speed (i.e. friction)dependant (which is why it works for blacktop/ constant speed) but the 75% height of tyre test like in the link above does give the best average footprint/shape for the sand, again gives different pressure front and rear depending on load.

So my tip is take the time to work out your car/tyre pressure calibrations

another good resource is the "experience" tips from pink roadhouse notes

http://www.pinkroadhouse.com.au/Pink...essure-pdf.pdf

Thanks Al.

The pink road house figures for a big 4wd look pretty close to the 20% reduction on placard pressure for track recommended by Michelin - 23psi front/31psi rear.