Tyre pressures, doing my head in!

[Baytown]

Hi everyone.

Im intimately aware of and practice tyre pressure changes relative to the Off Road surface being traversed, however I’m frustrated over my being unable to work out my Highway pressures, especially for the rear tyres.

Im running 40 psi in my 265/75/16 Wrangler Mud terrains, on my heavy 110. However, the ARB pressure sensors report that tyre pressure rises up to 50 psi in the rear when hot from running.

Ive tried increasing cold pressure to 45 psi but still get an over 6 psi pressure increase when the tyres are hot, especially when towing.

Any suggestions on correct tyre pressure to run?

Thanks.

Ken

[incisor]

Try 50 to start with

What is the tyres nominated max pressure ?

[Tombie]

6 psi on an LT isn’t a problem.

The 4 psi *guideline* is just that.

I wouldn’t sweat it, if the temperature on the TPMS isn’t excessive then don’t worry.

[Eevo]

common. my 40psi cold goes up to 46psi when driving

[Zeros]

I run the tyres on my 110 at 40psi front and rear unloaded. 45-50psi rear loaded. All highway pressures, measured cold. Many 235/85R16 LT / AT tyres run up to max 80psi.

[DiscoMick]

Have you checked the tyre pressures recommended on the door placard? Big difference front to rear.
I'm running 34 front and 45 rear.

[Zeros]

... it all depends on the stiffness of the tyre / sidewalls.

[Tombie]

And how much understeer you’re trying to induce [emoji41]

[justinc]

...and whether or not the vehicle needs a weight loss program...😣

[trout1105]

A lot depends on the ambient temperature, In summer I usually run at 36psi and winter at 40psi with an empty truck.
With a big load on and a boat on the back I just keep it at 40psi winter or summer because with the extra load the tyres heat up regardless of the outside temperature.

[Zeros]

Yes good point about ambient temps. ...IME A stock Defender front end with a steel bullbar needs 38-40psi. 40 in winter for sure. Placard levels are for no bullbar, 36psi may be ok. ...the weight of the driver has nothing to do with it of course 😇
Rears - yes minimising weight inside / on roof is everything, though with a 1 tonne load 45 may be too low. 😎

[DieselDan]

I've currently got almost the same as DiscoMick in the new ATs I've had fitted. 34 front 44 rear, fronts up 4 and rear down 4 from the placarded numbers.
Got the tyre place to change them from the 40psi all round that they initially set.
Carrying a bit of weight, but not too much, just a rijidij front bar and a set of drawers in the back. Plus the spare wheel carrier.
I'll try and do a pressure after the run to work tomorrow and see what they come out at.

[CraigE]

OK to throw something else into the mix there is an engineers calculation based on car weight that is readily available on line, I used at least a dozen variants to ensure they were all the same. You can run whatever pressures you like, but have a tyre fails and the tyre distributors will start quoting adequate tyre pressures.
So technically it will also vary on how your car is loaded.
I went through this last year with Maxxis and Tyrepower (needless to say wont be buying anything through either ever again).
Basically end of life of tyre though still 2 mm above wear markers, had 4 out of 4 tyres fail dramatically.
Straight away statement was made these tyres have to be run atr 40psi. Well 4th set of the same tyres and this was never mentioned ever. We ran off tyre placard by Holden which was 36psi. Did not want anything from them other than to make sure they stated in writing tyres had to be 40 psi. The actual calculation using the correct method showed an unloaded car to be run at 32psi and loaded around 36psi, so their 40 psi was bull****, but they will use this.
Then told me should be run at 50 psi which is max for this tyre dependent on load. Tried to tell us they had been run at low pressures which was rubbish always at least 36psi-38psi.
So bear that in mind when selecting tyre pressures, all of us with 4x4s could be in trouble running at different pressures.
There was a heap of other stuff such as statement made about running 17" wheels and tyres as well (which they sold an fitted to the car). Car can legally have 18"
Then also statements about modified suspension, when was stock standard.
Consumer protection where absolutely useless and their so called motor vehicle expert did not have a clue, stating there was nothing to show we were not told?? Other way around nothing anywhere to show their advised pressures.
So bear all that in mind when playing with different pressures.

[weeds]

For me I’ve kept it simple for both the defenders I have had regardless of weight 40psi front and rear.......

If I was to get serious than I would first want front and rear axle weights.......most assume there is a difference between them and take a punt on the different pressures front and rear. Ken yours is a heavy weight therefore knowing axle weights would be handy.

I remember many years ago an engineer from a tyre manufacture was telling us the best way to set tyre pressures was to measure from the ground to the centre of the axle. This is to ensure all four tyres are inflated to the same height given all four corners would be a different weight. Kinda made sense.......

When my defer is in daily drive from there is only 120kg difference between front and rear axle weight, throw driver and passenger in the difference would be less.

[Zeros]

...another perspective ...like everything on a Defender, over time you get to know it like an extension of your body and soul. Engine and drive train by feel and ear, handling by feel and intuition, rattles by ear and feel, tyre pressures by sight and feel. I can see and feel how many tyre lugs are in contact with the tarmac, how much bulge there is in the sidewall, how the suspension is riding in relation to tyre pressures, whether a change in psi is needed given the load.

Over 15 years / 400,000 km on two Defenders, I’ve had 6 sets of tyres, only two punctures and 5 have lasted an average of 80,000km in often harsh conditions. 38-40psi front and 40-48psi rear, on road, depending on conditions and load has proven to work for me. In the soft stuff I’ll drop them down depending on conditions. But I don’t subscribe to low pressures in rocky conditions as it makes the sidewalls too vulnerable. I would have done at least half those kms on harsh rocky outback roads.

[DiscoMick]

I find about 34-36 on the front works well on most roads. On the rear I vary it from about 42-46 depending on conditions and if towing the camper.
Of course, I lower those for sand and mud.
The stiff sidewalls on the ATs seems to mean not much difference in bulging no matter if the pressure is 34 or 44.
I also adjust the rear airbags depending on if towing or not.
I would think that 40 all round would make my Defender too harsh in the front and too soft in the back.
It's interesting that LR on the vehicle placard recommends such a large difference in pressures between front and rear on the Defender, much larger than the recommended difference on our previous D1.

[Tote]

Defender 130 with Hankook MTs I run 36 all round empty increasing to 46 in the rear depending on load. This gives the best balance between comfort and handling for me on my vehicle.

Regards,
Tote

[PhilipA]

What does the tyre placard say?
Regards Philip A

[DiscoMick]

From memory, my door placard says 32 front and 46 rear, which shocked me when I bought it.

[PhilipA]

From memory, my door placard says 32 front and 46 rear, which shocked me when I bought it.

Yes , unless you have a big heavy bull bar and winch a 110 is quite light in the front and for comfort 32 sounds about right. My d2 is 28.

If you have bigger tyres on ,ie bigger air volume like a 265 75 16 then the pressures can be lower as the air volume is more.
I run my D2 at about 30 front and 35 rear ( 40-42 towing) with 255 70 16 . I have done 60Kk on my BFGATs and have 8-9 MM left with even wear. Just had em balanced and the car came back with 40-42 all round.LOL

The rear on a D2 and I guess Defender assumes a full load so you can probably go down if just tootling around.
Regards Philip A

[weeds]

On mine, daily driver mode

1100kg front axle
1220kg rear axle

Says to me have same pressure front and back....I might try a few psi less.

[jon3950]

My placard (MY16 110) says 30 front and 48 to 65 rear depending on load.

When it was unmolested I thought these pressures were a little low in the front and a little high in the rear. I ran 32-33 front and 46 rear.

Now with bar and winch up front and constant load in the rear of fully packed drawers I run 34 front and 48 rear. On a trip I tend to bump the front up to 36 and the rear up to 50-54 depending on load. I usually set the front to what I want then set the rears so they are bagging about the same. I’ll drop them about 6psi when I hit the dirt, otherwise I start losing fillings.

Cheers,
Jon

[dromader driver]

light truck tyres. Usually running 28-30 front with 34 back around town. pacific highway trip plus 6 psi. fully loaded book figures. logging roads etc at less than 60km/hr drop back to around town pressures except when fully loaded.

ARB steel bullbar and steel tray. 1700kg empty [happycry][thumbsupbig]

[donh54]

Placard pressure would relate to the Original Equipment tyre. Change brand/construction/type of tyre/fitted extras,, the placard then becomes virtually meaningless.

[weeds]

Placard pressure would relate to the Original Equipment tyre. Change brand/construction/type of tyre/fitted extras,, the placard then becomes meaningless.

Didn’t the puma had different options for type of Tyre?.....does that mean the placards on puma would be differ depending on the type of Tyre fitted?

[donh54]

Didn’t the puma had different options for type of Tyre?.....does that mean the placards on puma would be differ depending on the type of Tyre fitted?Must have had a factory option for the different tyres. Difference between pressure for an 6 ply passenger type tyre, and a 10 ply LT could vary widely. Even similar construction across different brands can require different pressures to achieve similar traction / load capabilities.
I think the answer is to try the placard pressure, then adjust according to ride and load, until you get the best compromise.
At least the OP is thinking about his tyres! Lots of people don't!

[TheGrumpy]

My Puma came from factory with 50psi in the rear and spare, the front was lower - maybe 36ish.
Their were at least two choices for tyres. Also, if you optioned HD wheels you got HD springs so more variable....

[Tombie]

Of all my Land Rovers. Even when fully laden. I have never run a tyre above 42psi..

Ever....

And I’ve never had a puncture in any of them offroad.
Only puncture was a steel spike debris on the D4 LHR on a highway at 110km/h.

In 30 odd years I’ve had a collective total of 2 punctures - both LHR and both a foreign object on a sealed road.

All my tyres wear evenly and the ride is balanced.

[trout1105]

I am with Tombie, I have Never exceeded 40psi in a 4WD tyre and also haven't had that much tyre dramas.
I have always replaced my tyres BEFORE they get too old/worn and I have always checked the tyre pressures regularly and I think this is the main reason why I haven't had too many problems.
As for the tyre placard, Well that goes out of the window as soon as you change the type/size from the original factory fitted tyre/rim.

[DiscoMick]

I notice the Haynes manual for Defenders up to 2016, which arrived yesterday, says 28 front and 36 rear, which seems low to me.

[Tombie]

I notice the Haynes manual for Defenders up to 2016, which arrived yesterday, says 28 front and 36 rear, which seems low to me.

Rides fine stock like that.

Add a bar go +2
Add some load +2-4

[DiscoMick]

Actually, I checked tonight and I wasn't quite right from memory. It's actually 30/48.
Here's what the door placard says:

https://www.aulro.com/afvb/images/imported/2018/05/237.jpg

[DiscoMick]

Interestingly, the Haynes manual for 2007-2016 Defenders has different numbers (28/38):


https://www.aulro.com/afvb/images/imported/2018/05/238.jpg

[Tombie]

Interestingly, the Haynes manual for 2007-2016 Defenders has different numbers (28/38):


https://www.aulro.com/afvb/images/imported/2018/05/238.jpg

I wouldn’t trust a Haynes manual..

They don’t even list the fitted size!!!

[DiscoMick]

Yes, I also noted the absence of 235/85/16s in their list.
Later, in Reference 1 under turning circles, they show 265/75/16 for the 90 and 7.50 x 16 for the 110 and 130.
No idea why. Is it just an English thing?

[B.S.F.]

Why different pressures for Japan and the rest of the world ? If it's got anything to do with CDL, please, please ignore this question.
.W.

[DiscoMick]

Why different pressures for Japan and the rest of the world ? If it's got anything to do with CDL, please, please ignore this question.
.W.I wondered that myself.

[bee utey]

Why different pressures for Japan and the rest of the world ? If it's got anything to do with CDL, please, please ignore this question.
.W.

Japan new issue tyres were probably a different load rating. Note the line: "Pressures apply only to original-equipment tyres." etc.

[DieselDan]

I've currently got almost the same as DiscoMick in the new ATs I've had fitted. 34 front 44 rear, fronts up 4 and rear down 4 from the placarded numbers.
Got the tyre place to change them from the 40psi all round that they initially set.
Carrying a bit of weight, but not too much, just a rijidij front bar and a set of drawers in the back. Plus the spare wheel carrier.
I'll try and do a pressure after the run to work tomorrow and see what they come out at.


I've actually got 35psi front and 44psi rear I found out when I measured them cold this morning.
After my 30odd km trip to work (town stop-start traffic, then a good 20+km of 80-100kph) they were 38psi front and 48psi rear if that info is useful to anyone!

[DiscoMick]

It's interesting the way tyre jockeys tend to just stick in 40 all round and ignore the recommended differences front to rear.

[Tombie]

It's interesting the way tyre jockeys tend to just stick in 40 all round and ignore the recommended differences front to rear.

Anybody believing Tyre fitters actually have a clue is deluding themselves [emoji6]

I mentioned it before; I have a relationship with a local tyre store - they order in the tyres. I remove, fit, balance and install them back on the vehicle. I even do my own alignments (and taught them how to do it on D4s).

I regularly get calls to come put vehicles in and out of TTM.