Ultimately I'd ask, what do you really want to achieve?
Fitting bigger tyres is one thing, but really you shouldn't need a lift for bigger tyres. Or if you do, you are probably doing it wrong
If we think about what happens off road, the suspension should extend and compress. A lift is arguably just 'extending' the suspension when sat on level ground. But you still want it to compress. So your tyres still need to fit in the arches under compression.
There are several things we can do if the tyres don't fit in the arches. The cheapest is to trim the arches. But obviously this is not easily reversible and can be hard to keep tidy.
A body lift is another option, as this raises the body away from the chassis where the suspension points are. So will give more wheel clearance. But fitting a body lift can be a real pain. I'm not even sure if any are sold for the p38.
Lastly and a solution often used on Defenders is to run extended bump stops. Which physically limited the amount of up travel (compression) available, to prevent rubbing. But IMO this is usually a cheap cop-out as it ultimately reduces the flex of your suspension. On a purpose built off road rig this might not be an issue if you can still get the total travel you desire, but on relatively stock setups it wouldn't be my choice.
Also, on a p38 the bump stops are unique. They are like rubber springs, designed so you can sort of drive on them should the EAS fail. And I'm yet to find anyone offering extended ones. So you'd have to fabricate something yourself.
Ultimately this means you may want to really consider what size tyres you want to run.
Warning: On a p38 with EAS over large tyres may leave you stranded should the EAS fail. This is because when on the bump stops, only marginally larger tyres will foul the inner arches and even have the potential to prevent you applying steering lock without body damage. Moving the vehicle in this state will result at minimum in damaging the tyres.
On my p38 I'm running some 255/70R16's which come in at 30.06" tall. This makes them very similar sized overall to a 31.10.50R15 often found on a Series or Defender (and many Jeeps). But it is only marginally taller than the factory tyres (mine were 255/55R18's, which are 29..04" tall) by about 1". When my EAS failed it did damage the tread lugs moving the vehicle. So I'd be very wary of going taller on EAS. As some failures and faults can cause all 4 corners to sink to the bump stops.
I believe a 265 section would probably be ok in terms of width. But I noted my factory tyres rubbed the rear chassis under full compression. So wider on stock rims would likely be an issue here. I'm running aftermarket rims with a slightly wider offset. But going wider might result in the tyres hitting the outer wheel arch lip on compression.
I do know of some people running 33's on a p38, so they can fit. But it probably isn't something I'd do personally. I'm also running the side steps and mud flaps on mine, which means what I'm running really is about as big as I can fit.
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That's enough tyre talk.
If you want to 'lift' the vehicle. There are several ways. Obviously the easiest is via the High suspension mode on the dash
Which as has been mentioned can be re-programmed to a higher setting.
Personally I found even the factory high setting gives a poor and bumpy ride off road when you compare to coil spring counter parts (Disco, RRC, Defender etc). This is because the EAS works by increasing pressure in the air bag to raise it and thus increasing the spring rate too. Ideally you want a soft spring off road and a stiff spring when in the lower high speed motorway mode. But the EAS offers the reverse with soft squishy suspension in the low modes and stiff suspension off road.
There are other ways to 'lift' the vehicle. You could look at some lift blocks (not sure if you can buy them, but I'm sure you could in past years, or you could make them with relative ease). Essentially this is just a block to put between the bottom of the air bag and the axle, to 'raise' it up by whatever amount you want. You can do the same thing with coil springs. In the case of the EAS, you'd just need a block that the spring can mount too, while still securing to the axle.
This will give you the lift and will not effect the stiffness of the air bag when off road and will still give you the full range of EAS modes, although always x" higher for each mode, depending on the size of blocks. You'd not need to change anything else for this to work.*
*Height sensors might need reprogramming.
But there is an issue with lift blocks. And that is, you are now more likely to become cross axled or lift wheels off the ground. The reason for this comes down to available suspension travel.
On a pe38 it is the shocks that physically limit suspension travel for the most part, at least in terms of droop or down travel.
When the vehicle sits level on the ground, the shock will be partly compressed and partly extended. This means the wheel can move up or down as required. When you 'lift' a vehicle, either with blocks or by reprogramming the EAS, you extend the shocks more to account for the increased ride height. But this means that there is less available down travel than before, e.g. (using made up numbers).
If 'standard' when sitting level you had 4" of down travel. But you lifted by 2", you now only have 2" of down travel. If you wheel falls in a hole that is 3" deep, it will now be floating in the air by 1", where as a standard setup would still have the wheel on the ground.
But there is more. This effect is compounded by the fact that you may also loose some up travel. This will be because as you compress the airbag, it will increase pressure. So it will get harder to compress it fully. With either EAS re-programming or blocks, you may find the weight of the vehicle simply isn't enough to compress the spring to the bump stops (or same point it did standard). This too will result in you lifting wheels more often and becoming cross axled more easily. And is often the case why so many D2's (and Defenders) when modified perform worse off road than standard vehicles. Which you see quite often at events and lots on YouTube.
Increased ride height and clearance can have some benefits, so it is viable to go down this route if you want. But it does come with limitations, that on more challenging terrain will show up.
Ideally what you really want to do is
increase the
total amount of
wheel travel. For up travel and compression we know there is a limit set by the bump stop (or the maximum compressibility of a standard setup). So when modifying the suspension for off road ability, we want to preserve this up travel. However, we also want to get more down travel too. As this will massively help off road. And it will mean, if we do lift the vehicle, we will still have plenty of available suspension droop.
In order to do this, we need to fit longer shocks.
Longer shocks will offer more down travel, as they will extend further. In an ideal world, longer shocks also often mean revised mounting locations. As a longer shock might also be longer when fully compressed than a standard compressed shock. But there is usually some wiggle room. And normally you can get away with +2" longer shocks without needing to look at modifying the mounting points and without really impacting compression.
The trouble on the p38 is, there are not many off the shelf longer shocks available (although with enough time & effort, I'm sure you could buy other shocks that would work). But there are a couple of brands offering direct fit longer shocks.
But the EAS is an issue at this point. The standard air bag will not have enough length to handle the extra suspension droop, which will result in the bag failing and being pulled apart (I've even done this with standard shocks).
So you will need to solve this issue. Longer air bags is one option or you could run some suspension lift blocks.
The Arnott Gen 2's might be ok, but you'd need to check. I can't recall their specs.
Ideally you want the Arnott Gen
3 air springs. But these are stupid money, but are designed for extra suspension travel. They also offer a unique feature in that when extended, they offer a softer spring rate. They do this by some clever design that reduces surface area of the piston when inflated. So the Gen 3 solves the issue of poor off road ride and gives soft springs for off road and stiff springs for high speed. But be prepared to sit down with a stiff drink when you look at how much a set of 4 will set you back!!
For extended shocks you'll also need extended brake lines (which there are kits, but get the correct model year!!). Or have some lines custom made.
You'll also need to unclip and secure the ABS sensors as they won't be long enough in their stock location.
I also think you'll need to look at the height sensors too, either extended or relocating. And some reprogramming to set all the heights.
If you go for a coil setup instead of EAS it removes the issue of the EAS failing, so bigger tyres are not an issue in this sense. And removes the need for the Arnott Gen 3's or messing with the height sensors and reprogramming. But you'll still need to do the brake lines and ABS sensors.
Hope this helps.
This is mine with some info on what I've done and why:
