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What pressure to run MTRs at in large 4wd ???

Posted: Thu Jan 24, 2008 8:12 am
by Hof
Hi all,

Well I bit the bullet and got a set of 285/75R16 MTRs.. Seem great so far!!!

Just wondering, they are on a Patrol and will be carrying a bit of weight when we take off next week..

What kind of pressure are people running in Patrol/Landcruiser size 4wds??

Cheers,

Hof

ps, I searched and read the threads on generic pressures, just want a reference for MTRs on this particular vehicle :D

Posted: Thu Jan 24, 2008 8:25 am
by grimbo
no such thing as a generic presure. Put what the tyrre placard says then go for a drive for about an hour then recheck. If the tyre pressure has gone up more than 4psi add some more and repeat exercise. You will find the right pressure for you. Also make sure you test your pressure with your own guage each time. Of course it will change abit with the load carrying, ambient temperature, road surface etc

Re: What pressure to run MTRs at in large 4wd ???

Posted: Thu Jan 24, 2008 9:22 am
by bogged
285's on my GU I ran at high 30's front and rear, no issues so far.
but as Grimby says, tis trial and error.

Posted: Thu Jan 24, 2008 9:29 am
by nastytroll
we run 34/32 front to rear in gq wagon 32/30 in ute. I work it on feel vs traction.

Posted: Thu Jan 24, 2008 10:12 am
by RO8M
nastytroll wrote:we run 34/32 front to rear in gq wagon 32/30 in ute. I work it on feel vs traction.
Not sure that this is a good thing... You want quantitative analysis of the tyre, not subjective.

Again, as Grimbo said, approx 4pound rise in pressure from cold to hot is your target.

Disclaimer: To qualify, this would depend on exactly what you want from your tyres. I'm no expert (by ANY strech of the imagination) but there would be a variety of different things you could be looking for from your tyres: Life, traction on tar, traction in hard sand, soft sand, mud etc... Talk to an expert (Ryano from fourbys gets good raps); not for internal use, keep out of reach of children, individual results may vary.

Posted: Thu Jan 24, 2008 10:31 am
by ISUZUROVER
I have 285/75-16 MTRs on my IIA ute (about 1950 kg unladen (tools, recovery gear and and spare only).

When I first bought them I tries 36psi but the tyres were far too wallowy in the corners. Increased the pressure to 44-46psi and they were great. I have about 40-50k km on them, and they still have about 75% tread. Just did 7000km Bris-Perth on them, and they hardly lost any rubber.

I run them at 8-10psi for serious offroad stuff. 20psi on sand or when heavily laden offroad.

Posted: Thu Jan 24, 2008 11:19 am
by nastytroll
All vehicles are different, with more then 30psi in the rears on the ute all it does is turn tyres on corners. with the wagon if we ran it harder it made the ride uncomfertable.
I never said my tyre preasures were optimal only what we run. I would assume a tyre that spins on most corners would wear faster then a tyre running slightly under preasure.
Our patrols dont get fully loaded often, but then I would still only inflate them to what was comfertable. Obviously if the tyres are wallowing they need more air which is why we run higher preasure fronts.

What Grimbo said is the correct formular.

Posted: Sat Jan 26, 2008 11:07 am
by Hoonz
i was running 35x12.5 MTRs on 15x8 sunnies on a GQ ute
12-15psi in the rear
15-20 in the front for crawling slow stuff then take it up to 25psi if your gonna go a bit harder

MTR on 80 series LC

Posted: Wed Jan 30, 2008 9:00 am
by pridhac
G'day

I run 33x12.5 MTRs on an 80 series. According to the weigh bridge at South Windsor tip my 80 weighs 2.8t. I have done the 4psi test on my MTRs. I read somewhere that tyre pressures should change by 4psi from cold to hot. I run my tyres at 35psi cold, and after several hours of fully loaded with camping gear + family and towing a loaded 7x4 trailer on the freeway, they measure 39psi.

So according to the 4psi rule, 35psi is the correct cold pressure for my setup.

Cheers

Chris