<span class="highlight">Tyre</span> <span class="highlight">Pressures</span>

I also have a prado with the same size tyres and can concur with Phil G. The placard is useless.

Ran the same pressures as Phil G suggests for half a lap and not a single puncture or tyre problem.

any recomendations for a 100 series running 285/75/16's fully loaded.

Evan

Phil
Your partly right part 1....wrong part 2 , I deflate a little on gravel because a very tight tyre will have no give flex and stones will pierce , if the tyre has some flex it is much less likely ,

depending on the weight carried 32/32 on gravel, secondly this is a 4x4 , pressures should be same front and rear.

Test the theory with a kids balloon , blow it tight and poke it with a biro..BANG, get another and half inflate it and it will depress much further under the same force .

Of course there will be some who have some funny idea's like an old bloke who lives in the Molong Caravan Pk , owns a commodore ute ,runs 60psi , I walked away scratching my head , he only uses it around town .

.

I allso agree with Phil G's pressures , i keep it simple and use 18, 28, and 38 , 18 for sand and other slow going stuff 28 for dirt gravel such as the PDR and 38 for the black top.

40-45 in the rear seems awfully high to me. Why such a big difference from the front. You're not suggesting that a full load in the back is going to be 25-30% heavier than that b-----y big motor at the front. With 45 in the back it must feel like you are driving a road roller. I run 36 all round fully loaded, including towing a van and a full roof rack and have never had a problem. Have done 160k's in my 2000 Prado and just put my 3rd set of tyres on. (70k on original Grandtreks and 80k from BFGs) I've only ever had one puncture - on the Oodnadatta track in 2001 and that was because at that stage I didn't know to reduce pressures for dirt roads.

tessa

Gday Doug,
I think you and I are saying the same thing on Gravel. My answer was tailered to a fully loaded Prado, which is almost always a few hundred kilos lighter than a fully laden Troopie.

Regarding equal pressures front and rear: That would be true if the weight distribution was equal (optimal). But the Prado is a station wagon, and most station wagons are loaded so that most of the extra weight is behind the rear seat (rear axle). That has the effect of levering up the front end, so the rear tyres carry a lot more weight than the front when loaded. Thats just the way it is with Station wagons, and on the Prados, its hard to change that.

Tessa,
Fully loaded, you could take your vehicle to the weighbridge and find out. But can I suggest you do a simple test, and that is to measure the length of your tyre's footprint when fully loaded (just need 2 rulers in front of and behind the tyre), and then inflate the rear tyres until the length of the footprint is the same as the front. It may surprise you how much pressure is required to make the tyres the same. As I explained above, its very hard to get equal weight distribution in a wagon. In my traytop, its easier - anything heavy goes forward of the axle, which is where all my water, fridges, extra battery etc go.

40-45 psi are normal pressures for a LT construction tyre - they usually have a max pressure of 65psi. If you run lower pressures, on bitumen in hot weather, you'll see the rear tyres will get hotter and the tyre wear will be much greater than the front. It all depends on how much extra weight you carry, and how its distributed.

Cheers
Phil

Evan,
100series is a heavier vehicle, and most people add heavier accessories (side bars, rear wheel carriers, fuel tanks etc). But 285/75 usually has a higher load rating, so I'd be running same pressures as above, all other things being equal.

PhilG
I am quite happy with my current setup and have had no problems. AND, I regularly check my tyres for heat. However, perhaps I should have said that I take both rows of rear seats out and carry fridge water etc in front of the rear axle. Also run polyairs at about 24psi when fully loaded. BTW removing both sets of seats only takes about 15minutes - 8 bolts and 4 nuts on the second row, none on the third.
tessa

Doug T posted "secondly this is a 4x4 , pressures should be same front and rear."

Why?

Makes no sense to me.

Patrolman Pat
Use your brains mate. would you put different size wheels on a 4x4 front than the rear , You might but not me, with Auto Lockers you keep tyre size the same F/R and L/R , It might be fine to have different pressures when in 2WD but when in 4WD they should be the same .
You can come back again with all the excuses etc...I'm not interested , I know whats best for my vehicle ,

.

Phil
When my Troopy was working with all the gear/tools/water/furl etc it went 3060kg on the Tennant Creek scales , so it would be the same basicly if I were on a holiday trip.
,,,,,,lol If I got out it would have went under 3000kg .

.

Tessa, when we had the LC80 we ran 265/75/16 BFG AT's with 40-42psi. Tried lower pressures (35 up to 38) but they would wear more (scrubbing out towards the edges) and the handling was slightly degraded. If you are doing mostly highway km's you should be getting more mileage than that out of them and running higher pressure could well be the key.

Doug T,
there was no mention of auto lockers or any other type of locker, nor did they mention different tyre pressures on the same axle.
. When in 4wd one would assume a loose/slippery surface which would mean the wheels will almost certainly all be travelling different distances to each other, regardless of different tyre pressures front to rear. In 2wd or 4wd with the centre diff unlocked it shouldn't matter either.

I agree with Phils pressures....
Prado 2001 GXL TD with BFG/MTs 265/75/16s

I have also experimented with 50psi in the tyres for a pure freeway run from Wagga to Windsor & back. Fuel economy was 10.4l/100km.

I wouldn't suggest 50psi for anything other than good flat freeways as the ride is rather rough otherwise.

As to the front/rear weight issue, remember that the 90 series can take 159L of fuel, albeit that the sub tank is in front of the rear axel...its quite a bit of weight. Plus the spare wheel is hanging off the back door too. Fully loaded the car would be fairly equal front/rear with weight, perhaps a little heavier when full of fuel towards the rear.

Anyway enjoy your trip!

Patrolman Pat
whatever

Can't be bothered argueing over such petty issues

you do it your way,

I'll do it mine