Please read: Posts on 19" rims

Well said Tombie2. As I pointed out in another thread, after trying them and seeing what they're capable of, I'm personally more than happy with the MTR's on 19" rims. The steel 18" rims I have will not be for general consumption - I'll consider using them in off-road trials etc.

I am only following through with the hunt for forged alloy 18" rims because I said I would - not because I believe they're necessary. And for those who want more choice in 19" tyres, note that GG are still committed to bringing out an AT2 in this size, and that other manufacturers have the larger 275/55/19 sizes available now in Europe (although at this stage only in HT and Winter styles). I would seriously consider the Dunlop WTM3 in that size if it was available here.

Cheers,

Gordon

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Originally Posted by Tombie2

Firstly vehicles have to have stronger brakes the more power they produce. This is not about speed, its about the ability to decelerate a vehicle which can accelerate quicker than lesser powered versions.

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Sort of. Higher-performance brakes are fitted not because they are requried by law, but because it makes sense if you have a higher performance vehicle. The stopping distance tests could easily be met with far less braking capability than is fitted.

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Originally Posted by Tombie2

Then theres ventilation, a large rotor requires air flow around it to cool the brakes. The larger rotor also requires a larger caliper and this consumes room necessitating larger rim diameters / clearances.

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That's just the current design. It is possible to make a high-performance brake which fits into a smaller rim. But it's more expensive for various reasons including as you point out pad wear, and most owners like the larger rims, so why bother.

The point about ventilation is why steel rims should be viewed with caution as these do not permit heat to dissipate as well as alloys.

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Originally Posted by Tombie2

Land Rover, like all other (I hate this term) SUV manufacturers has listened to the market... A car like, 2500kg people mover with offroad capability and modern styling has been built. To think that the Australian market constitutes more than a drop in a bucket to the global sales base is laughable. Soccer Mums the world over love their big, car like SUV and its great brakes and larger rim tyre combo with responsive steering and handling.

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Precisely. The Aussie market is microscopic and the offroaders within that even smaller. So, we're not a significant influence.

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Originally Posted by Tombie2

Whats more surprising, is that the locals are looking to spend thousands of dollars on a 12.7->25.4mm profile change in their running gear. I mean were talking the need to slow your offroad pace less than 5km/h to protect the tyre compared to a slightly increased profile.

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Put like that who could argue? But then measure the sidewall width. Then measure it when slightly aired down with the tyre contact patch accounted for. Then look at the percentage difference, and I'm taking 17 to 19mm here or 25mm as the debate is really 17s on D4 2.7 vs 19s 3.0. It's a significant percentage.

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Originally Posted by Tombie2

PROOF OF CONCEPT is easy to achieve, however, are you willing to also put in the tens of thousands of kilometers of testing to ensure that the rim is strong enough to take the pounding that the OEM has done?

ROH for example make a rim for earlier Landrovers - the ZF I think, which fits, works and under use fatigues and cracks...

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That's a seperate discussion about all aftermarket accessories.

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Originally Posted by Tombie2

ALL OF THIS EFFORT would be better put towards lobbying a tyre manufacturer to make a mould for a 19" tyre that is 25mm LARGER than OEM.

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That would help except that then you'd probably get clearance issues. And in Victoria and NSW it wouldn't be legal.

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Originally Posted by Tombie2

Considering the law generally allows a 25mm larger tyre this is the SAME gain in sidewall as the rim change, with the added benefit of increased rolling diameter.

You can then have the CCF modified to correct the speedo error back to zero.

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15mm in Vic/NSW. 50mm elsewhere. Both limited by clearance. Given the push for ESC I think tyre diameter restrictions will just increase.

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Originally Posted by Tombie2

Towing, with the larger brakes trapped inside smaller rims with lower airflow is my idea of a nightmare... A long downhill on the brakes will definitely heat them up more than running std rims...

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And if you've gone for larger diameter tyres that would have a similar effect. If you're going downhill for long periods of time then the correct techniques need to be used to avoid fade regardless of the brakes. You could say that as a bullbar, winch etc adds weight that also affects the braking required and it's true. This is just another factor.

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Originally Posted by Tombie2

Offroad, the extra debris that can be trapped inside the smaller rim (including rocks caught between caliper and rim) will cause more damage and wear than sticking to 19's...

Anyone ever seen a rock caught between rim and caliper? I have...
It nigh on carved the rim into 2 seperate pieces and the owner was lucky not to suffer a dangerous failure. Rim was cut over halfway through the alloy.

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That can happen regardless of rim.

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Originally Posted by Tombie2

Let it rest, the vehicle is more than capable on 19's... Yes they are not as common right now - so buy a spare carcass before you go on that long trip... Get a repair kit and learn to use it. 19s, 18s, 17s and 16s make no difference... I've never staked a tyre offroad ever in any profile. And I'm offroad more than probably 90% of members here...

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Agreed the vehicle is highly capable on the right 19s. It would be better offroad in 17s. But do you need that extra capability? Each to their own, for some the answer is no, for other yes.

The repair kits do not cover 19s now, at least the ones I've seen. I'm glad you've never staked a tyre! By repair kits I mean those to remove and repalce tyres from rims, not plugs which do work on any tyre except for really high-speed roadies which are too weak.

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Originally Posted by Tombie2

I've sat watching accredited trainers and cringed at the old school, old thinking methods used offroad... This is not a 1990s vehicle, its a 2010 vehicle.. Build using modern techniques and modern technologies including suspension and tyres.. Combined with modern materials used for recoveries today almost the entire 4wd handbook is outdated.

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I agree there!

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Originally Posted by rmp

Put like that who could argue? But then measure the sidewall width. Then measure it when slightly aired down with the tyre contact patch accounted for. Then look at the percentage difference, and I'm taking 17 to 19mm here or 25mm as the debate is really 17s on D4 2.7 vs 19s 3.0. It's a significant percentage.

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Throw in the lack of LT tyres in 19"`compared with 17" and the 17" looks a good option except for the brake downsizing required. Give me 255/55-19 MTRs with Kevlar sidewalls and I'd risk the rim damage, as long as they're fitted to 19"x8" rather than 19"x9" rims and I had 2 spare rims.

There is a parallel to this debate for onroads. The decision I've taken to run all-terrains on 17s means my D3 doesn't perform as well as one on roadies using 19s. However, it's more than good enough for my purposes as I don't push the car's onroad limits, but I don't and can't argue I've lost nothing onroad.

In the same way, the 19" rim may be more than good enough for many offroaders and that's fine, but they can't argue no capability is lost or unrealised.

The brake downsizing isn't an issue for the 2.7 D3/D4 as no downsizing is required and the vehicles are designed for that size of rim. It's only an issue if you were to fit say 2.7L brakes to a 3.0L which would open up all sorts of interesting problems which I don't think would be cost-effective to solve.

255/55/19s probably aren't legal on 19x9 rims, need to check the tyre spec chart.

rmp & tombie,excellent posts

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Originally Posted by rmp

Precisely. The Aussie market is microscopic and the offroaders within that even smaller. So, we're not a significant influence.

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True,but i would be surprised if this topic has not been raised in other parts of the world.

There are also other vehicles around with similar power & weight figures to the D4 running 17" rims,either as OEM or as an option.

rmp has made all the points that need making on this topic I reckon - all well put.

Cheers

PS. The perspective of those who buy the D3/D4 will vary as to which is most important to them - ie on road or off road.

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Originally Posted by scarry

rmp & tombie,excellent posts




True,but i would be surprised if this topic has not been raised in other parts of the world.

There are also other vehicles around with similar power & weight figures to the D4 running 17" rims,either as OEM or as an option.

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The percentage of people who take the vehicles offroad is very small, and unfortunately their needs are often opposed to the needs of the non-offroading majority. Therefore, the latter's priorities are more important.

I agree with all said on this page, but I'd like to point out that there is an implication being made here that might confuse or put off people considering the 3 ltr TDV6. That is, that it is not capable enough to satisfy some people's off-road desires. I don't think this is correct. In terms of pure off-road capability, I haven't felt any lessening of capability from moving from a 2.7 ltr D3 on 17" competition muddies to a 3.0 ltr RRS on MTR's.

In terms of tyre durability and availability, yes, the 17" rims have an advantage. This is one variable however, that will almost definitely change over time.

Cheers,

Gordon

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Originally Posted by scarry

rmp & tombie,excellent posts




True,but i would be surprised if this topic has not been raised in other parts of the world.

There are also other vehicles around with similar power & weight figures to the D4 running 17" rims,either as OEM or as an option.

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There are very few other vehicles with 600Nm+ of torque that weigh as much as a D4 and are designed to go as well off-road. I can't think of any that come with OEM 17" rims? Edit: maybe the Porsche Cayanne?

Cheers,

Gordon

The LC200 weighs just as much, is as powerful as a TDV8 let alone a 3.0 D4 (certainly won't be left behind in a drag race) and comes with 17s standard in some specs. It also tows 3500kg and 750kg, another brake consideration. It has larger diameter tyres so say 18s on that car gives you more sidewall than 18s on say a RRS. It's really sidewall height is the issue, not the profile % which only gives an indication.

The VW Touraeg, relative of the Cayenne is another example. In its V6 diesel form it has a greater power to weight ratio than the TDV8 yet runs 17s. It is a little lighter though. The V10 monsters will slaughter any Land Rover diesel and I think they run min 19s or maybe 18s, I forget. They are just as heavy. Neither car is as good as the D4 offroad.

There is no need to run such large rims for brakes. It makes the job easier (cheaper) and looks better, but there is no engineering need.

Note that while the 200 has the raw grunt come the corners it'll flounder ;-)