Thread: 18" Compomotive Wheels

Originally Posted by Melbourne Park

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!

I'm pretty certain the maths isn't lost on Gordon .... nor towing, nor ..... blah, blah, blah ..... but especially the maths .... LOL!!!

Originally Posted by Melbourne Park

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, ...

Ok -sorry, the way you described it above was rather confusing - maybe it was my jet-lag.

Originally Posted by Melbourne Park

The formula is pretty simple. ..... 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!

Yes, I do tow - and I understand the simple machine / lever formulae. But note that the Disco with self-levelling suspension can't really be treated as a simple lever - LR state you can increase the GVM by 100kg when towing, which takes this opposing force into account.

The above plus the guestimates for all the other weights doesn't give you a meaningful result. For example, my tow-tongue + hitch weighs 8kg; and note as before, the LR kerb weights include a driver (so that's one heavy passenger at 160kg!); the Kaymar weight is too low etc etc.

It is definitely an issue, and the rear tyres may well have to take 55psi or more, for a large van.

Cheers,

Gordon

Originally Posted by Melbourne Park

Its off topic, but they do have a trick ... people get them certified to tow even 4.5 tonne. Yep - there are axle weights ... 1630 front, 1950 rear. The Disco is I think 1855 rear, but much less on the front - 1,450kg. But there is a weight that Toyota do not provide for the 200, and when its re-certified, they can ignore their axle ratings. I know it sounds quite wrong. I don't think Toyota would cover them for an axle failure though. But if a diff went, many would put in a 3rd party locker.

the beauty of the Disco though is you don't have to worry - or I did not - about putting in another suspension. The damn thing just works, no matter what you do. the only problem is, the tyres, and also, I don't feel good going over the tolerances.

I do think from what I've been told by people who tow vans like mine off road, that its speed that kills tyres (heat being a result of weight and speed) ... and with the Disco, one has to be wary because it hides speed and rough terrain.

A person I know has a newer model van than mine, and I offered for him to drive my Disco for a "test". He refused. He said he did not want to get jealous!! He used to own an Toyota dealership in the bush, and a radical change in the wheat arrangements back in the 1980s forced him to sell up. He is quite aware of the LR technology, but won't talk about it! He's setup extensively a BT-50 Mazda, but refused the Disco trial!!!

You've got to post a link to someone engineering a LC200 at 4.5t.

Originally Posted by Tombie

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.

I'm with Tombie on this. This is what I assumed was the problem, rather than the extra weight. The same problem happens when not towing and also on the trailer tyres. My thought is that the drive to the front wheels also tends to flick the rocks up more than would happen with a RWD car so the problem is worse for constant 4WD vehicles. My son's D1 travelling in convoy with us had the same problem with his MT rear tyres getting hammered. He had my daughter, two swags and their luggage with him and was travelling in front since the TDI 300 sets the pace on our trips! I tried to dodge the worst rocks that his car left exposed on the road.


However, I do agree that the rear tyres are working hard on the D4. My Kimberley has a draw bar weight of around 175kg when I weighed it. My old camper trailer was more like 250kg. All I had in the car was my wife and a Waeco Fridge plus some tools and my ARB twin compressor.


The weight of my Disco with all its fruit is 2740kg with half a tank of fuel in the main tank and no driver. It is biased towards the back I think, based on the deformation of the tyres when I let them down off road.


I will post some photos of my damaged tyre when I work out how to do it.

Hi Bob,


Maybe slightly off topic here. That's a very light D4 at 1740 kg?


Did a recent public weight bridge weight of 2835 +/- and that included all my fixed after market accessories totalling 236kg excluding 2 people, but included 65 litres of fuel.

The 236 was measured on a scale before fitting to get me a base line leading up to GVM.

Maybe the public scale system was out a long way?



Sorry bad format, attached my weight cheat sheet.

Regards


Gerald

Originally Posted by VK3GJM

Hi Bob,

Maybe slightly off topic here. That's a very light D4 at 1740 kg?

Gerald

Hi Gerald. Yes, you are correct. It was supposed to be 2740kg. I have edited my post.


I did a similar calc when I went to Cape York a couple of years ago and found that I had to severely ration the weight I was carrying, which included a roof top tent. I could only use about half of my long range tank to get within GVM but I ended up ignoring that and filling it up fully for most of the trip. That was when I weighed the car and got 2740kg.

Hi Bob,


That's great. I quickly went to my weight bridge certificate and back to my spreadsheet to see if I did something wrong, although knowing the vehicle is heavy anyway.


Can You do me a favour, can you measure the GEO rim with the 285/60R18 on it's own.


The standard 19" LR rim and GG 255/55R19 is 32.8kg


I have also updated my post to include a spreadsheet I use to calc my GVM, an interesting exercise.


My last trip, a slab of beer took me over. Lol...


Regards




Gerald

Originally Posted by VK3GJM

Can You do me a favour, can you measure the GEO rim with the 285/60R18 on it's own.

Happen to have one sitting in my driveway at the moment - 35.5kg