Right Pressure for new COOPER ATR 265/75R16

Submitted: Wednesday, Feb 22, 2006 at 17:06
ThreadID: 31042 Views:13332 Replies:8 FollowUps:8
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Hi people!
Just enquiring about the right Pressure for new COOPER ATR 265/75R16 on a 80 series landcruiser.... 36 ... 38 ... 40 psi???
Thanks!

Luca
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Reply By: Shaker - Wednesday, Feb 22, 2006 at 17:15

Wednesday, Feb 22, 2006 at 17:15
Ask the Cooper distributor, & keep a record of their answer, because believe me, when you try to make a claim they will blame incorrect tyre pressures.
They tried it with me, but I had made diary entry of their recommended pressure advice.
AnswerID: 156505

Follow Up By: Max - Sydney - Wednesday, Feb 22, 2006 at 17:58

Wednesday, Feb 22, 2006 at 17:58
If on the other hand, you want to maximise tyre life rather than set up the dealer to give you new tyres early, use the 4psi rule ie measure pressures cold, drive 40 km or so and check pressures again. If the tyre is inflated corectly, they will be about 4 psi higher than cold. Some say 6 psi rise for 4wd tyres.

It seesm to work well for me at 4 psi on BFG A/Ts.

Max
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FollowupID: 410584

Follow Up By: Shaker - Wednesday, Feb 22, 2006 at 18:11

Wednesday, Feb 22, 2006 at 18:11
I did say distributor, not dealer. I also agree with your rule of thumb.
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Reply By: Member - Willie , Epping .Syd. - Wednesday, Feb 22, 2006 at 17:23

Wednesday, Feb 22, 2006 at 17:23
" Lif eis like a big cake " You can't have your life and eat it too. Remember that Luca , it's very important .
AnswerID: 156509

Reply By: Willem - Wednesday, Feb 22, 2006 at 18:12

Wednesday, Feb 22, 2006 at 18:12
Luca

Dunno about ATR's but I run my STT's at 32psi on the bitumen as recommended by the tyre reseller.
AnswerID: 156514

Reply By: Member - Patrick (QLD) - Wednesday, Feb 22, 2006 at 19:06

Wednesday, Feb 22, 2006 at 19:06
I run my 265/75R/16 tyres fiited to a Patrol at 36psi on the advice of the fitting dealer here in Brisbane. Works for me.

Cheers, Patrick
AnswerID: 156528

Reply By: Member - Omaroo (NSW) - Wednesday, Feb 22, 2006 at 19:12

Wednesday, Feb 22, 2006 at 19:12
I was always under the impression that a tyre manufacturer could not be allowed to argue a claim if the user had the pressure set to what the tyre placard from the vehicle manufacturer stated.

I could be wrong - but that's always been my rule. Of course - that's for "normal" load conditions and on bitumen. Anything outside of this (sand, mud, heavy load, etc) is at the driver's discretion.
AnswerID: 156529

Follow Up By: Shaker - Wednesday, Feb 22, 2006 at 19:25

Wednesday, Feb 22, 2006 at 19:25
The manufacturers only concern is ride comfort!
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Follow Up By: Member - Omaroo (NSW) - Wednesday, Feb 22, 2006 at 19:54

Wednesday, Feb 22, 2006 at 19:54
I'm not sure that their interest is that shallow. I'm pretty sure that safety and handling dynamics come into their advised pressures too. Think about it - it's only to their advantage to present their vehicle at its best.... especially in this age of litigation.
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Follow Up By: Willem - Wednesday, Feb 22, 2006 at 20:20

Wednesday, Feb 22, 2006 at 20:20
Geez Chrispy

'00 Land Rover Defender TD5
'95 Nissan Patrol GQ TD42T
'91 Nissan Patrol GQ RB-30
'03 Jeep Grand Cherokee CRD

You starting a car yard? LOL

Cheers
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FollowupID: 410628

Follow Up By: Member - Omaroo (NSW) - Wednesday, Feb 22, 2006 at 21:05

Wednesday, Feb 22, 2006 at 21:05
Sorry mate - I forgot a couple! :)

'00 Land Rover Defender TD5
'95 Nissan Patrol GQ TD42T
'91 Nissan Patrol GQ RB-30
'03 Jeep Grand Cherokee CRD
'85 Saab 900 Aero 16 Turbo
'80 Saab 900 Enduro Turbo (limited factory run - 12 made, 5 left)

The Saabs are not good off-road.
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FollowupID: 410637

Reply By: Member - Luxoluk - Wednesday, Feb 22, 2006 at 20:19

Wednesday, Feb 22, 2006 at 20:19
Hi Luca.
My approach with the Coopers S/T is:

Towing or (heavy@ 3.5T) 40front /45rears
Genaral highway 40
Around town 35 for comfort
On the dirt 25
In the sand 15 to 18
In the sh#t 10

So far no punctures (wish I hadn't said that) and good wear pattern
Cheers

AnswerID: 156542

Reply By: Bob Y. - Qld - Wednesday, Feb 22, 2006 at 21:11

Wednesday, Feb 22, 2006 at 21:11
Luca,

Run 32 psi all round in same size as yours, though BFG AT's. Might kick rears up to 36, if carrying a load. Works in the Diamantina country, and on blacktop down to Brisvegas.

Hooroo...
Seen it all, Done it all.
Can't remember most of it.

Lifetime Member
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AnswerID: 156557

Reply By: P.G. (Tas) - Thursday, Feb 23, 2006 at 20:45

Thursday, Feb 23, 2006 at 20:45
G'day Luca. It never ceases to amaze me how freely folk with the best intensions give out bad advise on here.

In answer to your querie, EVERY vehicle is different! If you have the same model vehicle, same tyres, same springs, same shocks, same accessories, similar driving style then they will all run the same pressures, otherwise they WILL be different.

I have Cooper S/T's (265/75R16LT) on my bog stock GUIII Patrol, 3 litre manual with 50mm raised HD King Springs in the front and EHD Kings in the back, all controlled by Koni Heavy Track shocks adjusted up 1/2 turn on the front and one full turn from there softest setting on the rear. I rotate the 4 of them every 5,000k's and after 13,000k's of fast bitumen and dirt road driving they have worn 1.7mm, and I like having my fun through the corners.

I run 39psi front and 37psi rear and nearly everyone I have spoken too tells me that is way to high, but I believe the wear figure and handling speaks for itself.

To work tyre pressure out for yourself, here how I did it.

1. Have your vehicle weighed on a weighbridge in it's normal "everyday use" form, include a full tank(s) of fuel, all the gear you normally carry and a passenger or 2 if thats what's normally in there. First, weigh the front axle, then weigh the rear axle.

2. Look on the side of the tyre and Cooper supply a maximum rated load at a maximum pressure. NEVER exceed this maximum pressure figure. My Coopers have a maximum pressure of 80psi (550kpa), at rated load of 1550kg's, the previous Bridgestones (265/70R16 Duellers, D693's I think) had a MAXIMUM pressure of 36psi at their rated maximum load, big difference! If your tires don't have this information, a quick email to the Australioan distributor will fix this.

3. Now, start with the front axle weight figure and divide it by 2, mine are in brackets (F - 1320 kilo's divided by 2 = 660kilo's per tyre). Now divide the maximum tyre pressure by the rated maximum load number (80psi divided by 1550kg = 0.0516) Now multiply the answer by the amount of weight on each front tyre (0.0516 X 660 kilograms = 34.06), so the starting point was 34 psi for me.

4. Now repeat the same calculations for the rear.

I kept monitoring heat build up over the next week until I arrived at my 39psi cold F and 37psi cold rear, which give me a nice 3-5psi heat build up after an hours highway running.

The upside of all this troublesome work is a vehicle that handles exceptionally well, especially in the wet, brakes in a straight line, steers where you point it, has a firm but not harsh ride and excellent, even tyre wear IMHO. The original Bridgestones were buggered on the rear at 26,000k's, never rotated I'm guessing.

Sorry about being long winded, I hope this answers all your questions.

Cheers,

Peter
AnswerID: 156746

Follow Up By: Member - Dedalus (SA) - Thursday, Feb 23, 2006 at 21:37

Thursday, Feb 23, 2006 at 21:37
Thanks! I think my total weight is 3.6 tonns .... At the moment I'm driving with 34 psi in front and 36 psi on the back... very good confort here in Kangaroo Island but I think not enought for Hiway driving .... maybe 36-38 fronf + 38-40 rear???

Thanks!

Luca

p.s. I have 50 mm lift kit from OEM (springs + shockers) , cargo barrier, a full rook rack (4 legs) , alluminium bull bar + me, my whife and my 5 monts old daughter ....
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Follow Up By: P.G. (Tas) - Friday, Feb 24, 2006 at 11:59

Friday, Feb 24, 2006 at 11:59
G'day again Luca. The figures you suggest are at best a guesstimate, and you MAY get away with them, but I believe it is better to be sure than sorry.

I have done some homework for you. I'm assuming the tires are 10 ply 265/75R16LT Cooper ATR's. They have a listed load carrying capacity of 1550kg per tire and the assumption is also they have a maximum rated pressure of 80psi@20 degrees C (same as the S/T's) .

I don't know about your weight distribution between front and rear, so I will guesstimate about 60% rear and 40% on the front. Working on as gross weight of 3.5 tonnes, I came up with these figures.

Front 36 psi + 2psi for heat build up + 2psi for high speed highway driving = 40psi as a starting point.

Rear 54 psi + 2 psi for heat build up + 2psi for high speed highway driving = 58psi as a starting point.

The rest is up to you to work out. I strongly recommend no more than 6psi heat build up after 1 hour of normal highway driving, if you are after comfort, but preferably aim for the 3-5psi heat build up if you want to get the best out of your vehicle and tyres.

Remember, if you get more than 3-6psi build up the tires need more air, and if you get less, lower the pressures, and always check them before you move off in the morning. A kilometre of driving to the local servo will throw the whole process out of wack.

Heat is a tires worst enemy. It is the major cause for blowouts, tread separation and fast tread wear. Many tires have been branded duds or hopeless for the want of a bit of air.

Hope this helps.

Cheers,

Peter
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