tyre Pressures

JDO · Jun 25, 2018

landmannnn said:
Generally no. Tyre pressures are about maintaining the tyre shape on the bit that contacts the road.

The best way of testing is to put a broad stripe of chalk across the tread, then drive in straight line for a few yards. The chalk should wear off evenly, if it is too much in the middle, reduce pressure, too much at the edge increase pressure.

There’s also the “4PSI” rule which says you test the pressure cold, drive a few miles to warm them up, then check the pressure again. You want an increase of 4PSI. If less, then they were overinflated. If more, then they were under inflated.

I’m 90% sure this is an old bushman’s myth but plenty of people still swear by it.

duffs54 · Sep 16, 2018

Tyre pressure for my truck please

hello, Malc can't find it in the handbook, we have a 2014 NP300 2.5dci, the tyres say:

Goodyear Wrangler: MHS 25J/65R17 110FF

We only use it as a family car so not laden, but we are getting a caravan soon so if someone can help with pressure for both scenarios please,

Thank you x

landmannnn · Sep 16, 2018

Just use the guide that is stuck to the inside of the driver's door aperture.

doctorchopper · Sep 23, 2018

Also never trust the gauges at the petrol stations, they are notorius for being out as they are abused on a regular basis, thrown on ground be people who don't care. The new digital read out on the machines may be ok though

gfromleeds · Sep 23, 2018

JDO said:
There’s also the “4PSI” rule which says you test the pressure cold, drive a few miles to warm them up, then check the pressure again. You want an increase of 4PSI. If less, then they were overinflated. If more, then they were under inflated.

I’m 90% sure this is an old bushman’s myth but plenty of people still swear by it.

Sounds about right i run my 22s at 38psi all round and according to my tire pressure monitor on a 15mile motorway run the pressure goes up to 41/42psi

freemansteve · Sep 23, 2018

doctorchopper said:
Also never trust the gauges at the petrol stations, they are notorius for being out as they are abused on a regular basis, thrown on ground be people who don't care. The new digital read out on the machines may be ok though

It makes no difference if a reading is digital or analogue - what counts is if the machine is calibrated or not ....

An interesting idea is about the plate in the door jamb the specifies "no load" or "cargo load" pressures.... If you check and adjust pressures to suit cargo load, with no cargo, and then add the cargo, you'll find a substantial pressure difference. Which begs the question as to whether you set pressure actually under the load, or prior to the load. I do the former and find that when the load (800kg) is removed, you have lower pressure than you thought. Try it!

doctorchopper · Sep 24, 2018

freemansteve said:
It makes no difference if a reading is digital or analogue - what counts is if the machine is calibrated or not ....

An interesting idea is about the plate in the door jamb the specifies "no load" or "cargo load" pressures.... If you check and adjust pressures to suit cargo load, with no cargo, and then add the cargo, you'll find a substantial pressure difference. Which begs the question as to whether you set pressure actually under the load, or prior to the load. I do the former and find that when the load (800kg) is removed, you have lower pressure than you thought. Try it!

Sorry what I meant was the digital ones would be less abused as the gauge isn't in the filling tip so less likely to get hammered around, still wouldn't trust it though

landmannnn · Sep 24, 2018

freemansteve said:
It makes no difference if a reading is digital or analogue - what counts is if the machine is calibrated or not ....

An interesting idea is about the plate in the door jamb the specifies "no load" or "cargo load" pressures.... If you check and adjust pressures to suit cargo load, with no cargo, and then add the cargo, you'll find a substantial pressure difference. Which begs the question as to whether you set pressure actually under the load, or prior to the load. I do the former and find that when the load (800kg) is removed, you have lower pressure than you thought. Try it!

You also gain a couple of psi when the tyres get warm.

freemansteve · Sep 24, 2018

Yep. 39C near Seville, and 100km/h the rest of the way does not help!
But we got here OK on Saturday, and my birthday is today....

Love the V6 for pulling a load quietly.... Some serious long drags to above the height of Snowdon on the Ruta De La Plata

ArchJuke · Jul 10, 2019

I put on some 18" Grabbers and consigned the old tyres to the shed for now.
Got a bit of mileage to do this weekend so I went to check the pressures - even though I fully trust my garage.
Using a supermarket digital display airline, I found 40psi in the fronts and 35psi in the rears!
Close, but no cigar, guys!

landmannnn · Jul 10, 2019

Although on average they were right

tyre Pressures

JDO

duffs54

landmannnn

doctorchopper

gfromleeds

freemansteve

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landmannnn

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