D4 Axle Load Tyre Pressures and Bridgestone Dueler A/T d697 LT 265/60r18 114s

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Originally Posted by shanegtr

I base my tyre pressures from axle load and tyre max load/pressure. Weather its right or not who knows, but I find it works as a good starting point. The tyre max load and pressure information is on the sidewall. Use single tyre max load not dual obviously.

(Max tyre pressure / Max single tyre load) * Axle load /2(divide by 2 as the max tyre pressure/load is for a single tyre and that second part of the equation is for axle load so 2 tyres)

Therefore in the OP's example, (with a tyre max pressure of 80 psi and max load of 1450kg per tyre) = (80/1450)*1970/2 = 54psi. Thats fairly close to Bridgestone's recommendation of 51 (although Im not sure of the OP's tyre load - my calc was for a load rating of 121)

** edit, just reread the first post - load rating 114 = max load of 1180kg per tyre:
80(Im assuming the max tyre pressure is 80 here)/1180 *1970/2 = 66psi

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Shane, I've used the same logic for years with mobile crane tyres and been very successful at saving money and wear.

My maths was a bit simpler (because I am). But the same non the less. Work out what the tyre manufacture says to put in at Max weight.. Work out weight as a percentage. Within 10% was good enough.. Apply that percentage to pressure.

We had 20psi over in most tyres.

I once had 70psi in a Hilux rear tyre. Yes. It was very heavy. And all over the back axle.. But was perfect. Great advice Shane

My experience with them was they are rubbish. Many failures before i moved to some AT3's and have had no issues since running same pressures and conditions.
DO NOT recommend.

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Originally Posted by TuffRR

My experience with them was they are rubbish. Many failures before i moved to some AT3's and have had no issues since running same pressures and conditions.
DO NOT recommend.

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Can see from the tread they’re been run under inflated.

Heavy sidewalls - which the D697 has, are much more susceptible to heating up, if pressures aren’t correct for conditions.

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Originally Posted by Tombie

Can see from the tread they’re been run under inflated.

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I was looking at the wear around the sidewall.

The road surface tread pattern looks ok but the deflated pressure (the red dirt up to the damage line) shows the low pressure run on gravel roads was far too low or for too long at too great a speed.

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Originally Posted by 350RRC

I was looking at the wear around the sidewall.

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Centre tread is much less wear too, compared to outer blocks. A sign of under inflation.

This has lead to heat build up in that sidewall.

I concur with previous posters. Under-inflation will show up as wear on the outer edges of the tread and less wear in the middle. I'm running Maxxis 980 light truck tyres and use the 6psi rule of thumb. Towing a 2.5 tonne off-road caravan I've found that it is relatively easy to overload the D4 rear axle if the boot is filled (fridge, tools, other luggage) - redistribute load. I've also found that 45psi front and 50psi rear (at 20 Celsius) results in reasonably even tyre wear over 60,000 km. Any reduction for off-road is a cautious 20% max. with much reduced speed. Another rule of thumb is that each change in temperature of 10 degrees results in a change of 5-6% pressure. The van runs on 65psi, but that's another story. TPMS is great for peace of mind.

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Originally Posted by David Hannett

After discovering the sidewall damage (photos) on both rear tyres on our D4 I have learnt a few thing about D4 axle load and tyre pressures and am after any advice or feedback or points of view regarding our choice of tyres and loading and if there are better tyre choices out there please.

D4 SDV6 3.0L 2011 with no added-weight modifications except roof rack carrying 4 Maxtrax, one spare wheel and one spare tyre - 2 adults, 2 dogs, recovery kit, 80L fridge, tools, bits and pieces

On leaving Sydney a year ago we fitted four new Bridgestone Dueler A/T d697 LT 265/60r18 114s to existing Compomotive wheels and have covered around 16,000 km towing about 95% of the time a 2.5 tonne (fully loaded) hybrid camper. Mostly sealed except for Cape York, Savannah Way, Oodnadatta track and we’re currently located in Perth doing maintenance before heading to northern WA.

The rear tyre sidewall damage (photos) was discovered by chance when the wheels were off and it is weirdly only on the inside faces of the sidewalls, not on the outside faces (someone may have insight as to why this is).

Before leaving Sydney, we had weighed both D4 and camper and were comfortable with total vehicle weights but on discovering the tyre damage we have re-weighed axles individually and this is what we found.

Firstly tow vehicle and camper hitched together to reproduce actual towing conditions and each axle weighed separately (all fully loaded including people, dogs, fuel, water, etc)

	Actual.	Handbook max.	Difference
D4 front axle	1250 kg	1450 kg	-200 kg
D4 rear axle	1970 kg	1855 kg	+115 kg	(6% over)
Camper (single) axle	2310 kg
Total all three axles	5530 kg	6740 kg	-1210 kg
Tow ball weight	250 kg	350 kg	-100 kg	(10% of camper)

Secondly Vehicles weighed separately and unhitched (the D4 is a bit out because the driver was jumping in and out)
D4 2920 kg
Camper 2530 kg

So the D4 rear axle is 115 kg over by 6.4%

We had been running tyre pressures against the placard.
Sealed Unsealed
D4 front 36 28
D4 rear 43 30
Camper 50 30

Bridgestone tell us that for the rear axle load we should have been running 51 psi on the rear tyres sealed and wouldn't be drawn on unsealed. Front pressure were ok.
Apparently this information about load and pressures is not published anywhere?
And we didn't suspect how marginal we are with D4 rear axle loading not that we are assuming anything will break as a result?[bighmmm]

We don't seem to have many other options - unlike conventional caravans, redistributing weight in the camper doesn't offer much as it’s a 4WD design with the axle well to the rear and a long nose extended drawbar and the tow ball weight is about right as it is anyway. Maybe move the fridge forward, chuck out some tools, put spare wheel on the bonnet, put the people on a diet and send the dogs home?

So to continue using these tyres we need to go to 51 in the rear and maybe a modest reduction on rough roads

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Interesting as today I replaced 5 tyres for sidewall cracking and I'm concernerned on the implication of axle loading, as I rotate tyres regularly.
The tryes were BFG which over the years I have not had any issues with. The set that failed where 1/2 life in my past experience.
Hmm I need to research this isssue furtheer as we travel around Australia.

I've had sidewall cuts on 2 of my Duellers (although not as bad as these) with 50k on them and have since moved to another brand.