Thread: Tyre pressures, doing my head in!

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.

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.

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.

...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.

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.

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

What does the tyre placard say?
Regards Philip A

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