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?
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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