Recommended on-road tyre pressures

[RVR110]

I'm curious about the differential between the front and rear tyre pressure recommendations on the tyre placard on the B pillar in my 110 Puma wagon the rear pressures. The recommended pressure for the front tyres is 30psi and for the rear it is 45psi when lightly loaded.

I haven’t had the car on a weigh bridge but I would not have thought that the weight distribution would be skewed to the rear although I may be wrong. Does anyone know why LR would recommend such a marked difference between pressures?

[superquag]

My '95 Classic is similar, (withouty pulling the bonnet and looking...) around 28 psi front and 38 psi rear. - Same or similar ratio, loaded/unloaded.

When I bought it at 150K, the pressures were close to being equal... and my Viscous coupling died some months later. Can't say if the two are linked, though I suspect the ratio front/rear has a lot to do with the VC's life-span.

[87County]

I'm curious about the differential between the front and rear tyre pressure recommendations on the tyre placard on the B pillar in my 110 Puma wagon the rear pressures. The recommended pressure for the front tyres is 30psi and for the rear it is 45psi when lightly loaded.

I haven’t had the car on a weigh bridge but I would not have thought that the weight distribution would be skewed to the rear although I may be wrong. Does anyone know why LR would recommend such a marked difference between pressures?

I think you'll find that users of older 110s and deefers generally use substantially lower pressures than those placarded; (for comfort reasons). I know I do.

I imagine that if you experiment with sealed road pressures of 30psi or slightly less all round you may find it more comfortable. Off the tar you may wish to decrease them even further.

I believe that the 45psi is placarded to allow for the massive load carrying capability of the vehicle (which is rarely used)

the Puma has, a version of the LT230 tc so no VC to worry about as in post #2

[lrbob]

Hi, "The Land Rover Experience' by Tom Sheppard recommends:
Kerb weight(unloaded) 26psi f and 30psi rear
Max load: 27 front 48 rear
You could use the 4psi rule to fine tune. Pressure should increase by 4psi from cold to warm after a run. If less reduce pressure; if higher increase.
Hope this may be of use. Cheers.

[Quigley]

I'm running 26psi front and 28 rear on bitumen, unladen. I have the original tyres and my vehicle has done 18k. I find the recommended pressures make for a harsh ride.
I am aware of a number of rollovers where Rovers have had tyre pressures low in stone and sand conditions.
It seems that tubeless tyre beads can come away from the rim if under inflated and subject to high side load as in a sharp turn.
For unmade roads and for a loaded vehicle I think it is prudent to increase pressures up to 28front and 48 rear depending on the load and conditions.
My original tyres are wearing well and I would be interested to hear what mileages are being obtained with them.

[Loubrey]

I'm with you guys on the lower pressures. Guys spend a fortune on suspension upgrades where 26 and 28 Psi fixes all but the biggest issues on the ride. I personally use 1.8 bar (26 Psi) in the front, 2 bar (29 Psi) in the rear unladen, and 2.2 bar (32 Psi) in the rear under laden conditions (my personal guidelines for a Defender 90). I have in over 20 years of Landrover driving (civil Engineering and road building) never torn a sidewall sticking to these pressures. 110 and 130 drivers needs to find an optimum for the rear, but I do not agree with the blanket 40Psi rule (front and rear) that seems to be the standard out here in Northwest Australia.

Rollovers with low pressures would be driver error, especially on rock. When you are crawling (as you should in rock) you often get pretty severe articulation that can result in "bounce". If your tyres are rock hard, the equal/opposite force thing comes into play and a rollover is most likely. Soft tyres (not so soft to break beads and pinch sidewalls) will cusion impact, mould over all but the sharpest rocks and generally give you better grip. A sidewall will damage much easier when rock hard than when it's able to "give" when a rock pushes against it. Obviously unnesesary wheel spin will negate this theory and cut your sidewalls to pieces, hence Low 1st in rock!

This has worked for me over the years and there would be supporters of the other side of the coin.;)


Cheers!

[CraigE]

And you guys find it comfortable to drive at sub 30psi front tyre pressures?
I find at around this the front tyres get very squishy on the road at 110kmph and they wear uneven. Also fuel economy gets worse marginally.
I usually run around 40psi rear and around 38 front.
Not disagreeing, but it may depend on tyres too.

[LouisW]

I'm with you guys on the lower pressures. Guys spend a fortune on suspension upgrades where 26 and 28 Psi fixes all but the biggest issues on the ride. I personally use 1.8 bar (26 Psi) in the front, 2 bar (29 Psi) in the rear unladen, and 2.2 bar (32 Psi) in the rear under laden conditions (my personal guidelines for a Defender 90). I have in over 20 years of Landrover driving (civil Engineering and road building) never torn a sidewall sticking to these pressures. 110 and 130 drivers needs to find an optimum for the rear, but I do not agree with the blanket 40Psi rule (front and rear) that seems to be the standard out here in Northwest Australia.

Rollovers with low pressures would be driver error, especially on rock. When you are crawling (as you should in rock) you often get pretty severe articulation that can result in "bounce". If your tyres are rock hard, the equal/opposite force thing comes into play and a rollover is most likely. Soft tyres (not so soft to break beads and pinch sidewalls) will cusion impact, mould over all but the sharpest rocks and generally give you better grip. A sidewall will damage much easier when rock hard than when it's able to "give" when a rock pushes against it. Obviously unnesesary wheel spin will negate this theory and cut your sidewalls to pieces, hence Low 1st in rock!

This has worked for me over the years and there would be supporters of the other side of the coin.;)


Cheers!

Lou,

I found "Betty" face a very harsh low profile sport car drive on JLR press guide - so I lowered to your suggested 26F 29R - The ride is far better (nearly comfortable :)

however my tyre size are R18 - 265/65 any comment on this???

Regards Louis

[jimr1]

I think the best thing you can do is try different pressures , ones that suits you ! For example 28psi front and 35psi rear , if most of the time you running empty .You will get to feel what you like , breaking ,wet dry , cornering ect. You can always put a bit more in , or take It out . When I go off road I always let my tyres down , then put them back up once on sealed road . I don't think It is an exact science , different tyres behave different at the same pressure !!.. Jim :)

[alien]

Brace yourselves for what I run:p
110 with loaded draws, roof rack and bulbar with winch.
Defender and van on BFG Km2 mud tyres.
Rough axle weights on last trip, front 1.2ton, rear 1.8ton, van1.0.


On the black stuff(80% is 100km/h zones)...
110 only, front-42, rear 50.
Towing, front 44, rear 58(van 44).
On the dirt...
110 only in slow play mode, front 24, rear 30.
Towing, front 28, rear 36(van 28).


This is set using the 4Psi rule(After 1 hour of driving a 2->4psi increase from cold).
Any thing less on the black top leaves marks where the side walls contact the road when cornering:eek:
The handling is also reduced significantly so risk of a high speed rollover increases.


My concern with running lower starting pressures is it causes the side walls to flex more.
This can end up overheating the tyre casing which can in some cases lead to side walls failing.
This is often the cause of blow outs, often on longer high speed trips.

[Jeff]

On my TDi I used to run 36 all round, I have checked it with a TPMS and it conforms to the 4psi rule. If doing long dirt corrugated roads, I drop them to 30 or 25. I up the rears to 40 when towing. I run 235/85-16 Cooper ATRs and they are wearing very evenly.

Something I have found with the TPMS is if I get in the car in the morning and it is wet, the tyres are 1 or 2 psi down, also if I have been travelling on a highway and stop the pressure goes up, possibly due to heat build up. This would skew any gauge check if you did it then.

I haven't worked out what to run in the Puma yet, but will probably start with something similar. I want a TPMS that does trailer tyres too, so haven't transferred the old one from the TDi.

Jeff

:rocket:

[robh]

I've wrestled with this question a little myself. When I first got the puma 110 I ran 30's to 32 all way around then noticed the plate suggested 30 front, 48 back when loaded. I'm either carrying a lot of tools in the back (for work), or camping gear (for play) so I'm generally carrying a bit of a load. I'm running the standard Continentals (AT 235/85-16) and find them pretty good for my requirements (easy to somewhat difficult off road but not extreme, 80% on the black stuff)

My research concluded that matching "foot print" is more important than tyre pressure when matching front to back so I started with about 30 to 32 on the front and measured the foot print. To get a similar foot print on the back I needed about 45 psi. I agree it makes the ride a little harder but it makes cornering more stable, especially at highway speed, in my opinion.

So my advice would be, set the front to say 28psi for comfort, or 32psi if you like a harder ride, then match the foot print of the the backs to the fronts. Then test drive, test drive, test drive (which is the best part) till you find the level you like.

I do drop pressures a lot when off road. Say 25 front, 35 back for dirt road and the like, and 20/22 front 28/31 back for other stuff, depends on surface and conditions, even lower for soft sand.

Rob

[KzBushy049]

Those placard pressures don't allow for the fitment of bull bars, winches, spotlights ect on the front end. But do allow for a full load in the back. So it's all about finding the natural balance for your landrover, I like about 32 psi all round day to day, but that's just me

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[RVR110]

Thanks for all the comments - it's been interesting to hear the different perspectives. The comment about the bull bar was something I hadn't thought of. I'd heard the tyre foot print in relation to matching trailer tyre pressures to vehicle tyre pressures, but hadn't considered it in relation to front/rear pressures.

Several comments were made about the 48psi rear pressure noted on the placard as being for "load carrying". The plackard actually specifies 48psi for light loads (2-4 people) and a whopping 65psi when fully loaded with 4 people plus luggage plus trailer:

https://www.aulro.com/afvb/images/imported/2015/07/1226.jpg

[JDNSW]

Tyre pressure is always a compromise, which means there is no "right" pressure. Handling and fuel economy demand higher pressures, ride demands lower, as does traction - but not so low that tyres move on the rims or sidewalls are damaged. Tyre manufacturers demand higher pressures so that they get fewer tyre failures and longer life. And some vehicles require specific pressures to avoid handling problems.

To some extent it will depend on the type of tyre, and I have been told by one tyre repairer that LT tyres should never be run below 65!

My 110 has placarded pressures from 35/35 unloaded and below 105kph up to 60/65 with a load of over one tonne and travelling over 120kph.

In practice, I run at 35/35 lightly loaded and go up to 40/50 at full load, maybe 40/55 if towing as well.

John

[dromader driver]

er umm wonder where that placard was on my defa. must have faded....

[DiscoMick]

Unladen, on bitumen, I'm running 34/38 on the original GG TRs. Seems fine so far. Interested to hear what others are doing.

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