Thread: D4 v LC200

To me I would never fit smaller brakes if I was towing,I wouldn't fit smaller brakes for any reason and as far as getting stuck in the bush that happens everyday and has nothing to do with tyres.Today outback Oz is filled with people with no offroad experience,no mechanical experience and no common sense,just this stupid idea that there Toyota won't break down and if it does a phone call will have a tojo mechanic with them in double quick time with the parts they need.To travel in the outback you need to know how your vehicle works,a good supply of consumable parts and how to fit them,if you deside to go with only one spare,no fan belt,no coms and no idea it's a bit rich to then complain about not being able to get parts or tyres and the line about not made for Oz is the biggest load of BS I've ever heard.I would not think twice about taking a D4 on 19'' tyres on the same trip I did in my defender,I would be aware of the damage that could happen and drive accordingly,for caravaners it's a non issue,you can't take a 30' 3.5 ton van through central Aust so the tyre ''problem'' wouldn't come into it,they only block up the roads travelling from one park to the next. Pat

Originally Posted by ozscott

RMP said "the disadvantage of low profiles is rim damage, not a decrease in contact patch area. However, because LPs have stiffer sidewalls because they have less of a sidewall often in practice the contact patch is a little less than the equivalent high profile."


I agree with that mate but the converse is also true - high profile, even in light truck 8 ply sidewalls, when aired down sufficiently allow a very significantly increased contract patch, particularly lengthways (which is sand in particular is what you want - sideways not so much cause it sends up like trying to roll a log with a large face area like a wedge) whereas even at 5 pounds a very low profile does not lengthen out anywhere near as much.

Cheers

Not correct. All tyres only lengthen their contact patch, not widen it. Even at 8psi the sidewalls of a tyre won't touch flat hard ground. Obviously if it's soft then the tyre sinks in though.

If the construction, diameter, width and pressure of two tyres of different profiles are the same the contact patch length and width will always be the same.

If you air down say a 255/55/19 you get a nice long contact patch, just with the rim uncomfortably close to the ground.

RMP - my comment was correct. I was making the point that airing down lengthened contact area...which is what you are saying also. My point was about that being preferred to having wide tyres in sand - ie longitudinal increase compared to relatively narrow tyre is better than the same longitudinal footprint in a wider tyre - hence the log analogy. I have been sand driving long enough to know the difference and of course 4WD monthly did a very useful article using ink prints of tyres aired down. But as it happens there is a slight increase in sideways contact area on airing down as that article showed and that would be of help in sand at least - but that sideways tends to be more obvious on passenger tyres. Hope that helps.

Cheers

Hi Guys,

While were on the hijack..........

Just wondering about the smaller brakes swap, disregarding the possible insurance hassles, what is the difference between the larger and the smaller setups in regards to disc size and caliper piston number and arrangement?

From how I understood it, larger diameter (and width) discs don't necessarily add to the braking performance of a vehicle, at least in normal and short time harsh breaking situations, but the larger surface area of the disc will dissipate heat more effectively over a long period to reduce the likely hood of brake fade?

Increasing piston size, number, pressure and inclusive of pad surface area is what effects braking performance is how I was led to understand it?

Therefor, I think it would be possible to keep with the standard if not better breaking performance in a smaller rotor size if the calipers where upgraded as well, maybe an opening for the aftermarket somewhere to produce a wider yet smaller diameter, more efficient rotor with a high performance caliper that fits under a 16" wheel?

I think the reason OEM go big is.......

A - It looks flash and sells cars
B - Pound for pound, it is cheaper to develop and install larger and less efficient brakes as opposed to smaller and more technically advanced?

Dont forget the D4 with the 3 litre is essentially the same vehicle as the D4 with the 2.7.

You are legally allowed to travel down the same hill with the same caravan, travel on the road at the same speeds etc etc.

In fact it could be argued that a car fitted with 17" or 18" tyres that are light truck rated would better handle the extra extra loads generated by towing.

The other argument about Australia being such a small market is perhaps invalid as there are many other countries that would have similar problems with 19's i.e. Africa, South America, Russia, India, China etc. Whilst individually these may be small markets combined they would be a huge market.

We can only really hope that LR are listening to the only real complaint of the 3 litre D4 & perhaps provide an option to fit the 2.7 brakes on order or option a 18' wheel that will fit ie as discussed on this forum.

Regards

Chuck

Originally Posted by ADMIRAL

Put a 3 tonne caravan on the back and try a steep hill descent. Sorry I cannot understand why you would want to deliberately reduce the braking capacity.

The weight of the caravan is irrelevant as it should be taking care of its own braking.

I do agree about reducing braking capacity though.

Stephen.

if it can take care of its own braking( and it should--)
why cant it take care of its own stability?
oops sorry,,

The D3's brakes were just fine, so the 2.7 D4's identical brakes should also be just fine.