Thread: 18" Compomotive Wheels

No need for permanent lift or lock limiting with the 285x60's on a D4. Full articulation means hitting the bump stops and you can see on the GOE web page what rubs. It is very little and no problem at all. Since the 285's just touch in a couple of places the extra 1.25mm could make a slight difference but I still wouldn't expect any real problem with them. I only know what the 285's are like, however, from personal experience.

Originally Posted by BobD

No need for permanent lift or lock limiting with the 285x60's on a D4. Full articulation means hitting the bump stops and you can see on the GOE web page what rubs. It is very little and no problem at all. Since the 285's just touch in a couple of places the extra 1.25mm could make a slight difference but I still wouldn't expect any real problem with them. I only know what the 285's are like, however, from personal experience.

Thanks Bob, I should have read your post better!

Re the performance of D697 tyres. I have pretty serious chipping and lots of cuts to the carcass between the treads on my rear tyres, especially after the Birdsville Track and Great Central Road. One cut was showing canvas with a couple of threads cut also. This was with tyres at 28psi and towing a Kimberley Karavan. The fronts are perfect. Just the rears cop a beating.


I previously posted about the tread damage on my D697's on the Binns track and the consensus was that pressures were too high. I lowered them this time but had the same result, or worse.


No failures and absolutely no sidewall damage at all, though, and I will replace this tyre with another D697 as I think they are the best compromise for the work my car does. I will post a photo when I get my car back with new inlet manifolds, hopefully today.

Bob, on tracks like that the biggest threat to rear Tyres is always the front tyres as you've discovered...

2 things happen... Front tyres flick rocks into the rears which then run over them. Front tyres turn up rocks exposing edges which the rears then run over.

The first issue is even worse without front mud flaps.

Tombie, we've discussed rear weight issues before, and perhaps this is also effecting the rear tyres.

BobD has a Brown Davis LR tank, a Kaymar rear Bar too ... I wonder what the tow ball weight of the Karavan is? The mid spec. for the Karavan tow ball weight is 230kg.

The Kaymar with tyre would weigh 40kg, and because its behind the rear axle it adds 55kg to the rear tyres.

The weight of the extra fuel tank with 80 litres of fuel adds around 67kg to the tyres.

The 230kg trailer tow ball weight adds to the tyres 330kg.

The tow ball tongue with ball if it weighs 10kg would add 13kg to the rear tyres.

So, all up, that is an extra 465kg onto the rear tyres. The weight of the bull bar would remove some weight though from the rear tyres - I don't have the figures here for that but lets guess 65kg. So that is an additional weight of 400kg on the rear tyres. Plus their might be some things in the rear of the vehicle. Lets guess at 50kg onto the rear tyres - 450kg then.

Driver and passenger weight of 160kg adds 99kg to the rear axle too.

So all up so far, the rear tyres are getting an extra 550kg kg load onto them. The rear axle weight (although I do not know the tare weight of the rear axle, my guesstimate is 1151kg), would be with 550kg of extra weight, 1700kg of rear axle weight. The front tyres are having a lot less weight. I haven't included the main fuel tank either. The front tyres would be carrying about (I haven't precisely checked my spreadsheet) about 350kg less or about 20% less weight.

IMO rear weight is a real issue with tyres. Load weight on tyres is an issue with transport trucks, and it makes sense the same applies to 4WDs. Before I bought the Disco, I thought the rear tyres were a somewhat close to being overloaded on the Disco.

My tow weight is higher than BobB's likely 230kg though, so I am more concerned about the rear weight issue than most.

Incidentally, my figures above are based on a 55% tare weight being on the front axle, and 45% on the rear therefor. If the balance is 52% on the front axle, then my figures would show an extra 77kg on the rear tyres.

I have asked what the front rear tare weight is on the Disco diesel but no one knows ... strange that LR do not publish that figure.

I haven't taken the rear axle weight of BobB's vehicle either for the front battery - that's worth some weight off the rear tyres.

I saw a video of that South African chap who takes a D4 over the Baboon pass. He made it, but it rained and the vehicle slipped sideways and dinted a door and also a front bar and front side panel.

Interestingly he, he ran very high tyre pressures on his tyres. At the early part of his part 1 video (its on u-tube, he did it with a D4). He said they were so low profile, that he had to run high pressures to protect them, and the flex on such low profiles would have the edges get cut up in no time.

He had three criticisms of the D4: the Sat Nav (bad there and since fixed), the wheel diameter too big and also the silly Land Rover imposed 50KMH height restriction (he did not seem to know about Llams or even the GOE insert suspension raisers). He explained the reason for it was that safety wise the D4 met all Euro safety issues at 50KMH at raised height, but at over 50KMH the D4 did not meet some esoteric Euro safety ratings (I guess the moose test swerve thing that only racing drivers can achieve anyway).



This is a different approach to what Aulro guys seem to advise ...

These figures don't make sense? Adding 65 kg to the front axle doesn't remove 65kg from the rear. 45% of 160kg isn't 99kg?? 40kg for a Kamar + tyre is too low, but it doesn't magically multiply to 55kg. 13kg for the tow tongue?

Cheers,

Gordon

Originally Posted by Melbourne Park

Tombie, we've discussed rear weight issues before, and perhaps this is also effecting the rear tyres.

BobD has a Brown Davis LR tank, a Kaymar rear Bar too ... I wonder what the tow ball weight of the Karavan is? The mid spec. for the Karavan tow ball weight is 230kg.

The Kaymar with tyre would weigh 40kg, and because its behind the rear axle it adds 55kg to the rear tyres.

The weight of the extra fuel tank with 80 litres of fuel adds around 67kg to the tyres.

The 230kg trailer tow ball weight adds to the tyres 330kg.

The tow ball tongue with ball if it weighs 10kg would add 13kg to the rear tyres.

So, all up, that is an extra 465kg onto the rear tyres. The weight of the bull bar would remove some weight though from the rear tyres - I don't have the figures here for that but lets guess 65kg. So that is an additional weight of 400kg on the rear tyres. Plus their might be some things in the rear of the vehicle. Lets guess at 50kg onto the rear tyres - 450kg then.

Driver and passenger weight of 160kg adds 99kg to the rear axle too.

So all up so far, the rear tyres are getting an extra 550kg kg load onto them. The rear axle weight (although I do not know the tare weight of the rear axle, my guesstimate is 1151kg), would be with 550kg of extra weight, 1700kg of rear axle weight. The front tyres are having a lot less weight. I haven't included the main fuel tank either. The front tyres would be carrying about (I haven't precisely checked my spreadsheet) about 350kg less or about 20% less weight.

IMO rear weight is a real issue with tyres. Load weight on tyres is an issue with transport trucks, and it makes sense the same applies to 4WDs. Before I bought the Disco, I thought the rear tyres were a somewhat close to being overloaded on the Disco.

My tow weight is higher than BobB's likely 230kg though, so I am more concerned about the rear weight issue than most.

Incidentally, my figures above are based on a 55% tare weight being on the front axle, and 45% on the rear therefor. If the balance is 52% on the front axle, then my figures would show an extra 77kg on the rear tyres.

I have asked what the front rear tare weight is on the Disco diesel but no one knows ... strange that LR do not publish that figure.

I haven't taken the rear axle weight of BobB's vehicle either for the front battery - that's worth some weight off the rear tyres.

I saw a video of that South African chap who takes a D4 over the Baboon pass. He made it, but it rained and the vehicle slipped sideways and dinted a door and also a front bar and front side panel.

Interestingly he, he ran very high tyre pressures on his tyres. At the early part of his part 1 video (its on u-tube, he did it with a D4). He said they were so low profile, that he had to run high pressures to protect them, and the flex on such low profiles would have the edges get cut up in no time.

He had three criticisms of the D4: the Sat Nav (bad there and since fixed), the wheel diameter too big and also the silly Land Rover imposed 50KMH height restriction (he did not seem to know about Llams or even the GOE insert suspension raisers). He explained the reason for it was that safety wise the D4 met all Euro safety issues at 50KMH at raised height, but at over 50KMH the D4 did not meet some esoteric Euro safety ratings (I guess the moose test swerve thing that only racing drivers can achieve anyway).



This is a different approach to what Aulro guys seem to advise ...

I did not say 65kg at the front would take much weight at all from the rear axle - I just said - or meant to say - that I hadn't taken any weight off the rear axle, and BobB has a bull bar, but it maybe alloy or steel, and have lights, but whatever it would take a bit of weight off the rear axle. That's all I meant to say ...

The formula is pretty simple. You measure the distance of the weight added, from the rear axle, if its behind the rear axle. Then you divide that into the overall wheel base. My calculations showed that for the rear tongue if it weighed 10kg, because its behind the rear axle ( I measured mine), it would add 13kg to the rear axle. Likewise, it would take 3kg off the weight off the front tyres. All weight added which is behind the rear axle, removes weight from the front tyres. You must know this surely? Maybe you don't tow ... but think about it Gordon!

If the weight is close to the rear axle but in front of it, then not all the weight is added to the rear axle. So if I put my fridge inside the vehicle on top of the rear axle, then all its weight would be added to the rear axle. If I put my 40kg fridge in the centre of the two axles, then 20kg would go to the front axle and 20kg to the rear axle. Its quite simple really ... as far as the bull bar goes, it does take weight off the rear axle, because its in front of the front axle. It doesn't make a huge difference though because its only just in front of the front axle, but it does make a difference.

But if anyone has a tare for the front and the rear axle, and the fuel load, that would be useful. LR don't provide a tare weight for the front and rear, or a distribution percentage of the weight for and back. They just provide the maximum weight allowed for the front and rear axles. It doesn't take that much to go over the rear weight. Especially if your towing and carrying passengers. Add a rear fuel tank and twin rear tyre carriers when towing with passengers with a decent tow ball weight, its extremely easy to go over the maximum rear axle weight.

Toyota have tricks to get over this - they do not specify all the maximum weights, so when a 3rd party changes the maximum towing ability and load carrying, the 200 series can still be legal. But that's way off topic - sorry for that!

We can argue about the maths, but the point is important - weight is a big killer and when you load up a Disco most of it is carried by the rear tyres.

More weight = more heat.

Tombie's point is also important and is exacerbated by additional weight.

Cheers,
Jon