Tyre pressure for the long road

[Alex Roux]

Hi all

Like perhaps several people on this forum, we are trekking with my Troll on the N1 from Gauteng towards the coast this holiday.
I am driving with 265/ 75 16'' at 2.5 bar (all-terrain)
Now I realise that tyre pressure varies depending on altitude and the heat generating from cruising at 120 for a sustained period.

q1: Is it important to check the tyre pressure at each stop on the way down to the coast?
q2: What sort of variation in tyre pressure should one be prepared to tolerate (while sticking to tar roads off course)?
q3: Anything else I should bare in mind?

Thanks for the help in advance
Alex

[Russ Kellermann]

I run my tyres at 2.3bar measured when cold before a trip with a load.

Test them at your first stop, if they cold then the tyre is too hard, if they very hot then the tyre is too soft. Should be a nice warm feel. I know many may say thats not accurate but its always worked for me.

[Chris Skinner]

Alex, what you need is a TPMS - tyre pressure monitoring system. I have one installed which I got on ebay for half the local price of these things.
It works absolute wonders - gives tyre pressure and temp as well as your battery volts. It also warns you when a tyre is too hot, too soft, too hard, or a sudden change in an of these parameters.
From my experience, if you set pressures at 2.5bar when cold, teh temp will go up 10-15 degrees or more on a hot day when travelling long distance, the pressure will also increase proportionally to the temp (boyles law I think) by approx .3-.5 bar if I remember correctly.
I do not set my pressures harder than 2.5 when cold, and this is a good median for all tar road sea level or highveld, even when towing heavy.

[Peter Connan]

I agree with both of the above, with a couple of adders:

Firstly, I beleive that on a fully loaded Patrol, the rears should be a bit harder than the fronts.
Secondly, a lot of people beleive in the "4psi rule", which states that if the tire is correctly inflated, then the difference in pressure between hot and cold will be 4psi or 0.26Bar.
Another way to determine the correct pressure for the load is to draw a broad line across the entire tread using chalk, and then drive a couple of hundred meters and see how the chalk is being removed. It should be even across the width of the tire.

The really fancy guys do it by measuring the heat in the tire on both sides and midlle, using a tire pyrometer, but I don't think we need to go there.

If you feel the heat of the tires at each stop, you will soon know if you have a problem as the one with low pressure will be hotter than the rest. In the absence of TPMS, this is as good an indication as measuring, and a lot less hassle.

[Chris Skinner]

Hi Peter, I discovered an intersting thing with my TPMS.
After driving a couple of KM's the back rear tyre is always 4-7 degrees hotter than any of the other tyres, and thus slightly higher pressure - Wilfred and Hennie also found this and eventually we realised that it is due to the exhaust running close to this tyre. Shows how accurate the TPMS is these days.

[Peter Connan]

Chris that's amazing.

There is certainly no doubt that these things are incredible, but there are a lot of things I need to spend money on before the TPMS gets to the top of the list. This feeling is of course likely to change the first time I lose a tire due to an undetected slow leak

However, I have had several punctures on this and other cars, and have never yet failed to detect them before damage ensued except once on a trailer. The fact that I am running 33" tires on 15" rims should also help here as the sidewalls are exceptionally tall, and I don't tow a trailer enough to justify it (at the moment anyway).

But TPMS is certainly on the list, just not anywhere near the top yet...

[Alex Roux]

Peter

This is perhaps a topic for a new thread, but my Christmas wish list of things to get for my baby is very long. TPMS is on there but also not at the top.
Then there is the list my wife has of things to do or get done in and around the house!
Do other members also live with this conflict?

Things to get for the Trol versus Other things for the house (new bathrooms, new curtains, you name it)

Maybe we should start a therapy group...
"Hi, I am Alex, and I love my Patrol..."

[Tinus lotz]

ja boet ek is ook lief vir my Patrol!!!!

[Peter Connan]

Alex, I have exactly the same problem, only worse.

Here's a little glimpse:

I need to fix my roof.
I need new gutters.
I want to build a carport with a fredlin hoist, to lift my roofrack off.
The boss wants a pool.
The boss wants a veggie garden.
I want (need) quite a lot of photographic equipment. (A spare battery, AC adapter, remote or cable release, tripod, and a few lenses might do it.)

I am not even going to talk about what I still need for my car.

In between all this, Pienkfoot mk1 will need a car one of these days...

[Tinus lotz]

En erens trou jy ook nog ne????!!!!krisis kom ons wen die lotto!