Advice for Disco 4 Buyers

[Disco4SE]

If you are looking at buying a Disco 4, I strongly recommend the 3.0Lt option and rear air conditioning.
I have had the 2.7 in the Disco 3 and had it re-mapped. Although I was happy with it, the 3.0Lt is sooooooooooo much better.
Pay the extra for the 3.0Lt. You wont be sorry.

[roamer]

x2 for above
Hey DISCO4SE have you tried to use your air suspension from access to off road more than once in a row, and have it take more than 2mins to rise second time
Cheers Ken

[Disco4SE]

Hi Ken,
No I havent tried that with the suspension as yet.
Must try.

Cheers,
Craig

[rmp]

OTOH, the 2.7 can take 17" rims, is considerably less expensive and has adequate power. The 3.0 is by no means an automatic choice over the 2.7.

[ADMIRAL]

If you are looking at buying a Disco 4, I strongly recommend the 3.0Lt option and rear air conditioning.
I have had the 2.7 in the Disco 3 and had it re-mapped. Although I was happy with it, the 3.0Lt is sooooooooooo much better.
Pay the extra for the 3.0Lt. You wont be sorry.

This has been raised previously. Yes the 3.0 litre is great, but apart from the dollars, it come down to what your intended use is. Notwithstanding the current research into 18" rims for the 3litre, being able to retro fit 17's to the 2.7 opens up the options for serious off road tyres.

Rear aircon? Kids in the 3rd row...yes I can see an advantage ! Not an issue for a lot of us though.

[Disco4SE]

Hi Admiral,
I was quoting the rear air conditioning more so for the 3 seats behind the drivers seat rather than the 6th & 7th seats.
The people in the 3 seats have their own controls and you dont have to wait for the front vents to filter through.
Had it in my Disco 3 as well. Works great

[gghaggis]

This has been raised previously. Yes the 3.0 litre is great, but apart from the dollars, it come down to what your intended use is. Notwithstanding the current research into 18" rims for the 3litre, being able to retro fit 17's to the 2.7 opens up the options for serious off road tyres.


A lot has been said about the inability to fit 17" rims to the 3.0 ltr RRS/D4. I'm not convinced that it's quite the show-stopper that is claimed, and I've certainly been investigating the issue closely!

Not-withstanding the rim size, you are limited to 32" max diameter tyres - period (unless you use shortened rods permamently, which is another can of worms). That somewhat reduces the choice of tyres regardless of the rim size, if you're talking serious off-road tyres. Basically Mickey Thompson MTZ's or Maxxis Bighorns in 17" sizes, and really only available as an oversized tyre - 265/70/17. Actually, if your talking serious off-roading, you can forget anything smaller than a 31" tyre anyway - no clearance, and very little tread depth.

If we're only considering AT tyres, then the current solution for D4 owners (won't work for the new RRS unfortunately) is to get 20" rims (LR or aftermarket), fit 285/55/20 LTZ's or similar and a set of SecondAir internal beadlocks. This will allow plenty of flotation at low tyre pressures (you can drop to 6psi with the beadlocks), and the beadlock itself protects the rim at low pressure. The sidewall is larger than the 255/55/19 tyres (in fact about equal to the 265/60/18 tyre size), so less rim damage at high pressure.

Not legal in all states of course, but then just fitting non-approved rim sizes (and the 17" rim is not approved for the D4, even if it fits) is a somewhat hazy area.

There's a lot more (and realistically, the Pirelli ATR or Goodyear MTR 255/55/19 is not a bad choice, still giving slightly more sidewall than the std fittings), but I'm on holiday and I've been told to log off and go enjoy the Great Ocean Rd, so maybe more later.

However, I AM in possession of the new Dynamic 4x4 18" rim, which I'll be trying on a new RRS (mine!!) when I get back to Perth.

Cheers,

Gordon

[rmp]

17s are approved for the D4. Check the placard on any of them, including the 3.0, and there will be a 235/70/17 tyre option.

What's legal vs what's approved are two different things. There are only four approved tyre size for the D4, but in fact there are many legal variations. The 285s would certainly be oversize in those states that limit diameter increase to 15mm. Whether owners care or not is a matter for the individual. Personally I'd always keep it legal, approved by Land Rover is another matter. Easier to talk your way into a warranty approval than out of an insurance decline.

I know people run oversize tyres on D3/D4 but there comes a point at which clearance is a problem and that may only be discovered a little too late, such as one owner who hit a bump at some speed and found some rubbing he didn't know existed.

Agree that larger tyres are required for 'serious' offroading, but IMHO for touring the stock size works just fine. I would only want oversize tyres if I was intentionally seeking out difficult tracks or competing, and only I do that in my Defender which has the stock standard size of 32" fitted. I do have this bigger-tyre argument on occasion with someone else who considers anything less than 35" as a toy car.

Just another opinion into the mix.

[gghaggis]

Wow - that was quick!! I was just going to edit my above post to say the 17" might actually be approved by LR for the D4 - it's on the placard (as RMP says).

Re oversize vs (near) std. If you are considering serious off-roading, in any Rangie or Discovery from the last few decades (and I suspect that this argument will turn on one's definition of 'serious'), you will need oversize tyres. LR has consistently fitted undersize tyres to these vehicles, when the competition fits 265/70 or 285/60 tyres. Their off-road prowess has suffered as a consequence, if only because of the size of the ruts made by other 4wds!

If you are considering touring or light-to-medium off-roading, then a decent AT tyre should be adequate. In which case, what's the real penalty of 255/55/19 ATR's vs 235/70/17's? Sidewall height is less by 1", but footprint at 16psi is similar. Rim damage is a little accentuated, but not onerous.

I think a lot of people are being swayed towards the argument that the new D4 is inadequate off-road (and there is some basis for the argument) by comparing the performance of HT tyres. On AT's, the difference between 17" rims (and std size tyres) and 19" rims is reduced significantly. I've had two clients come with us on training days with 255/55/19 MTR's, and they cruised through all and any obstacles that the 17" rimmed vehicles tackled, including sand.

Cheers,

Gordon

[rmp]

Yes, it turns on the definition of serious. For my part, I cannot think of a touring track anywhere in Australia I couldn't take my D3. Now if we go looking for trouble...that's Defender time but only because it's an older vehicle and I'm much less concerned about damage. I go out with cars that have larger tyres (had a car with 37s on my last tuff trip) and my Defender still gets places. Yes it would be more capable with taller tyres, but my approach is I want to challenge myself as a driver, not make the car more capable when it's already very good.

Yes good point -- the capability gap between 19 and 17 is reduced when the 19 has good offroad rubber. It's really the stock rubber is not very good offroad. Agree the contact patch is about the same for the same pressure, although the 17s do have an advantage.

It's not "only" 1 closer to the ground. That is true in absolute terms, but percentage wise we're talking from 126mm to 103mm. One inch makes a difference when there's so few inches to play with. Also, 19 and 20" tyres and rims are considerably more expensive than 17s.

On sand the vehicle's weight is usually about equally distributed and rim damage is not really a problem. Different story on rocks, or a tricky downhill where a lot of the weight is on one wheel.

For me the bottom line is 19s and 20s can and do work offroad, but not as well as 17s.

[gghaggis]

For me the bottom line is 19s and 20s can and do work offroad, but not as well as 17s.

Agreed, but remembering that the real-world difference is smaller when considering AT-shod vehicles (which all touring cars should be) and that the additional ability/power of the 3.0 ltr D4 will more than compensate for the difference.

Cheers,

Gordon

[Graeme]

fit 285/55/20 LTZ's
This size is theoretically 32.3". Does this size fit?
Should it be 285/50/20? These have 3mm (theoretical) taller sidewall than 255/55/19 - identical in my world.

[rmp]

Agreed, but remembering that the real-world difference is smaller when considering AT-shod vehicles (which all touring cars should be) and that the additional ability/power of the 3.0 ltr D4 will more than compensate for the difference.

Cheers,

Gordon

OK well that moves it into a 3.0 vs 2.7 debate not a tyre profile debate as power has nothing to do with profile...and rim issues aside the 3.0 is a lot more expensive than the 2.7. For many that'll be the deciding factor, especially as the 2.7 has adequate power. I do love the 3.0, but on the other hand, it's a lot of extra money.

[wombathole]

Doesn't the 3.0 also have a newer ZF gearbox than the 2.7? What is that worth in the real world of driving?

From Land Rover;
Fitted to both the automatic LR- TDV6 3.0L and LR-V8 variants, the upgraded ZF6HP28 Automatic Transmission features:
• Adaptive shift strategy which adapts to driving styles and surface conditions
• 10% faster shift response times (sport shift)
• Improved fuel economy through a wider range Torque converter lock up
The ZF6HP26 Automatic Transmission is fitted to the 2.7 TDV6 variants.

From Wikipedia;
ZF 6-speed auto
6HP19 — longitudinal smaller version of 6HP26
6HP21 — longitudinal 2nd generation of 6HP19 2007–
6HP26 — longitudinal 2000–
6HP28 — longitudinal 2nd generation of 6HP26 2007–[1]
6HP32 — longitudinal bigger version of 6HP26
6HP34 — longitudinal 2nd generation of 6HP32[2]

[ADMIRAL]

Doesn't the 3.0 also have a newer ZF gearbox than the 2.7? What is that worth in the real world of driving?

From Land Rover;
Fitted to both the automatic LR- TDV6 3.0L and LR-V8 variants, the upgraded ZF6HP28 Automatic Transmission features:
• Adaptive shift strategy which adapts to driving styles and surface conditions
• 10% faster shift response times (sport shift)
• Improved fuel economy through a wider range Torque converter lock up
The ZF6HP26 Automatic Transmission is fitted to the 2.7 TDV6 variants.

From Wikipedia;
ZF 6-speed auto
6HP19 — longitudinal smaller version of 6HP26
6HP21 — longitudinal 2nd generation of 6HP19 2007–
6HP26 — longitudinal 2000–
6HP28 — longitudinal 2nd generation of 6HP26 2007–[1]
6HP32 — longitudinal bigger version of 6HP26
6HP34 — longitudinal 2nd generation of 6HP32[2]

Off road all that transates to what ? I would think not a lot unless the conditions were pretty extreme. Perhaps we can persuade one of the mags to put the same tyre type and tread pattern onto a 2.7 & a 3.0 litre and do a comparison in extreme conditions.............but what would it really compare. The power, the gearbox or the tyre configuration. I suspect the gearbox used on the 3 litre has more to do with the power now being fed through it than anything else. ( particularly for towing )

As for the tyres, I will probably stay with the 18's on my D4, but look at a nominal increase to a 265/60. It has a minimal impact on rolling diameter. I have quoted this article previously, but check the December 07 issue of 4x4 Australia. A good article on low profile off road tyres, and one of the test vehicles is a D3. Yes it's old, but still a good read.

[Graeme]

Overlander have stated that they will have a 2.7/3.0 comparison in a month or so.

[rmp]

The gear ratios for the 2.7 and 3.0 are exactly the same. Fuel economy is better or will be once the 3.0s loosen up, but not by very much in cruise.

Something else re low profile, they give a rougher ride than high profile. Again not saying they're bad, it's just another pro/con to consider.

[gghaggis]

OK well that moves it into a 3.0 vs 2.7 debate not a tyre profile debate as power has nothing to do with profile...and rim issues aside the 3.0 is a lot more expensive than the 2.7. For many that'll be the deciding factor, especially as the 2.7 has adequate power. I do love the 3.0, but on the other hand, it's a lot of extra money.

Power and profile are somewhat related in terms of off-road ability, especially in sand. Up to a point, more power will compensate for the reduction in flotation. It's not just profile (sidewall height) that determines low pressure footprint. The radius of curvature of the tyre will also constrain the longitudinal footprint elongation, and for the same size sidewall, a larger diameter tyre (ie on a larger rim) will elongate further. So to a limited extent, the larger rim size compensates for the lower sidewall. Which is one reason why many people voice surprise at the lack of drama a 19" AT-shod D3 has in sand.

Where of course, low profile tyres are at a disadvantage, is sidewall and rim damage. Which is why I looked at fitting the internal beadlocks. They protect the rim and sidewall. Unfortunately there are none in the 19" size as yet, although Opposite Lock are looking into it for me (they make a 20" and a 19.5" size??!). Hence my comment on the 20" rim. But of course, that requires oversize tyres ......

As a tow vehicle, I'm sure the 3.0 ltr would be the better choice. And from all the above, I don't think the 19" rim will limit it in anything but serious off-road conditions (which is what I want to get around). Costwise I'm not sure about the D4, but doesn't the difference buy you a lot more than just the larger engine/gearbox?

Cheers,

Gordon

[rmp]

The cost does buy you more than just the engine, but even after you've added all the options to the 2.7 the 3.0 has it's still quite a difference. And add the cost of the tyres, 5 x 17 vs 5 x 19 (or 20). The difference is still several thousand and that's assuming you took all the 3.0 options which you may not want. For some that will not be any problem, for others they'd rather spend the money on tyres, bar, rack and carrier for the same price as another 40kw and 200Nm.

Re profile agree to some extent in principle - yes simply powering through at speed can see you across rather than going slowly relying on flotation. I do the latter all the time in my Defender ;-)

However, in the case of the 2.7 vs 3.0 both are pretty powerful and the power only makes a difference when you don't have enough of it, a car with say 200kw isn't necessarily going to have a massive advantage over one with 150kw, not like two cars with 100 and 150. As engines become more and more powerful they are output limited in the lower gears to the headline figure is rarely achieved. It also assumes that power can be brought to bear and in twisty inland tracks that is not necessarily the case. It's not unlike driving something like an M3 onroad, it's not often you can really utilise all that grunt. However, it's nice to have it.

Yes a larger diameter tyre will work better than a smaller one, but as you say that brings its own problems. I think a 19" rim is fine offroad....on a 37" tyre!

I agree the 3.0 would be the better towcar due to a much stronger engine. If all I was going to do was tow an onroad caravan that's what I'd buy for sure. Not that the 2.7's bad though.

A 19" D3 would be able to air down nicely and on sand the rim shouldn't be damaged...but do it often enough and sooner or later there will be damage.

[ozscott]

Has anyone with a D3/D4 tried the 19inch wheels on the sand - I mean by that deep sand and particularly towing in deep sand....how did it go cause I would be a sceptic about 19's in DEEP sand but I stand to be corrected by those that have tried it of course.

Cheers

[rmp]

That's what most of the discussion above is about.

GGH clearly has, as have I, although not towed. The short answer is the 19s work but not as well as 17s and there is greater chance of rim damage.

[ozscott]

Thanks

[Dingmark Jim]

Several times I towed on semi-soft sand (but not sand that when walking I would sink up to my ankles) with 19" MTRs on my V8 D3. Had 16psi on the MTRs and 12psi on the trailer (the old Goodyear HTs). Took a heavy throttle and it goes okay. I've also been on very soft (both powdery dry and ocean wet) with the MTRs at 16psi (up to Wedge Island in winter when the beaches are pretty cut up). Got well and truly stuck but then everyone on the beach was having the same problem. Maxtracks came to the rescue. The conclusions I reached from these sorties is:

The 19" MTRs at 16psi work better than I would have expected on sand. They're better performers in soft sand than were the 18" Cooper HT+, for comparison.
At 16psi, the rims would be hit by rocks and probably broken with 19" wheels, so I always have to stop and pressurise to 25-28psi as soon as I get off the beach.
Limits for getting stuck in 19" tyres is more due to the high weight of the D3 with all the air suspension weight. On two occasions, this caused the D3 to lean when on a sloping beach. leading to the tyres in the water-soft sand yielding and leaning over even more. Solution is to stop before getting into this situation.

To summarise, 19" wheels with MTRs are pretty good in sand, but need careful driving on sharp rocks to protect the rims. If I was going to drive mostly on very soft sand, then best would be a light jeep or Defender 90 with huge floppy tyres. Frankly tyre cost, not capability, is the big issue with the MTRs (think not much change from A$700/tyre:eek:). Finally don't assume that SWMBO will be willing to push out of sand (they keep novels in large purses for these occasions):p

[Tote]

We did a trip last September with a range of vehicles to Newnes and the Spanish Steps track which resulted in all vehicles except 1 ( a Patrol with 35" tyres) being winched up the far side. I was interested in the comparison between my D3 on 18" General Grabbers and my mate's 100 series on 32" MTRs. He has front and rear diff locks although wasn't game to use the front one unless he has to :p
Capability between the two vehicles was pretty much line ball even to the point of getting stuck at exactly the same place on the way out. Runnng 20PSI my tyres bagged nicely and I did not come close to the rim touching.
I've also had my truck on Fraser Is and had no difficulty in getting where I wanted to go.
I guess what I'm trying to say is that I would agree with RMP's statement above that there aren't many places that you would want to take a touring vehicle that the D3/D4 would be limited by the stock tyre/rim combination.
The only real reason I can think of to go to the trouble of getting 17" rims would be if I lived in a remote area and the cost of destroying tyres was getting too expensive or replacements were too hard to get.

P.S I also didnt mean the stock tyres, I meant stock size, the original wranglers weren't so good.
Regards,
Tote

[rmp]

To be precise, I said the stock diameter wasn't a limitation, at least to me and while I understand the advantages of a greater diameter I don't believe the tradeoff is worth it.

The stock rubber most definitely needs replacing for long-term offroad use, even dirt-road use. Yes, the vehicles can go places stock standard -- I've driven a RRS on 20" roadies around some very tough tracks -- but that doesn't mean to say it's a good idea.

Often people are looking to buy say 18" offroad rubber and if you look at the current tyre prices the savings you'll get by opting of 17s instead go a some way to covering the cost of the 17" rims, and you can eBay the 18s.

The 18" Grabber AT2s aren't standard and they definitely work better offroad than the stock Continentals.

[gghaggis]

According to my friendly tyre distributor .....

As the new Prado's and LC's are now specc'd on 265/60/18 and 285/60/18 tyres, you can expect a lot more maunufacturers releasing these sizes in Oz. Pirelli are already doing this.

Ditto with the 19" tyres (although mainly on 275/55/19), as Merc and BMW are using this size too. Dunlop's AT (3?) will be released in this size, Michellin already have a couple, but in the European market.

Cheers,

Gordon

[ADMIRAL]

According to my friendly tyre distributor .....

As the new Prado's and LC's are now specc'd on 265/60/18 and 285/60/18 tyres, you can expect a lot more maunufacturers releasing these sizes in Oz. Pirelli are already doing this.

Ditto with the 19" tyres (although mainly on 275/55/19), as Merc and BMW are using this size too. Dunlop's AT (3?) will be released in this size, Michellin already have a couple, but in the European market.

Cheers,

Gordon
That's good news for us with 18's as std.