Been a while... Time to clear out the iPad.
The 4 psi rule:
Can’t really remember how I stumbled upon this, maybe something in the comments to ASPW tyre video - I’m not against his suggestion of getting to know what your tyres look like, I’ve relied on letting tyres down by eye myself, but really why wouldn’t you use a gauge as well if you had one? - anyway, it’s a fascinating concept...
Originally Posted by Peter @ Aawen4×4
I use that 4psi rule everywhere, and for everything!! It works very well in ALL circumstances and across all variations that you can think of and a whole heap of others you never dreamed of! Use the tyre placard as a start point, drive for an hour, stop, and check the pressure. If it’s gone up by MORE than 4psi, your start pressure was too LOW, add pressure now! If it has gone up by LESS than 4psi, then your start pressure was too HIGH and you need to drop 2psi NOW! Those new pressures should become your start points for the next cold start!
And when you are off-roading, then use it the same way. Start with the guidelines that come from places like the Cooper Tyre Book, the Mickey Thompson guide to tyre pressure, even the prado4×4 guides above. Apply the 4psi rule, and adjust your pressures as you go. You will take only a sort while to work out what pressure is a good start for you, and by using the 4psi rule you can adjust the pressures to what is the optimum for YOU and your driving style, load, vehicle, conditions, temp, etc. AND remember that when you drop your tyre pressure by say 20%, you should also drop your top speed by 20%!! Tyre pressures lower, speed lower!
BTW, Cooper tyres tend to run a lower pressures than most people generally think, probably because the extra layer of belting in the carcass reduces the flex in the sidewall a little and reduces the induced temp increase as you drive. Enjoy your driving, and don’t get too worried by it all, do what you can without stressing, and live with it, it’s the best you can do at the time! Shouldn’t let a little thing like tyre pressures take away too much from the enjoyment of getting out there in your 4By!!
Originally Posted by Peter @ Aawen4×4
All this tyre pressure stuff came (some years back) from a tyre guru who had spent his working life in the back rooms of the tyre companies that spent mega bucks supporting some of the race teams. He had a wealth of knowledge, and had a career that included time with a couple of the large tyre companies, and some of the big names in international racing, as well as successfully running one of the more respected tyre development and testing departments in the world! I was very impressed with his down to earth approach and knowledge, and he spent some time explaining that despite all the computing power that had been bought to bear on the subject of determining the ‘optimum’ tyre pressure for a given tyre for ALL situations, they still hadn’t been able to get anything better than the ‘4psi increase after an hours worth of driving’ and it worked wherever they applied it!
Since then, I’ve seen it appear in lots of places, the latest being the Cooper and Mickey Thompson 4WD Driver’s Guides, where they have a section on tyre pressure, and they lay out the ‘4psi Rule’! They do suggest to use it only for bitumen road use, and despite being told by ‘the man’ that it worked anywhere, I too was a little slow to be convinced that it STILL works fantastically for Off-road use, surfaces, and conditions; it’s just that the pressures hafta be significantly lower to start with! I suspect that is the reason for the rider in the Cooper and Mickey T documents; either that or they are protecting their butt from some perceived potential lawsuit. But it’s worked for me driving trucks & buses, cars, 4WD’s, and even tractors of various sorts, in all sorts of conditions, heat, snow, rocks, sand, et al, so don’t be worried about applying it to whatever you are doing with tyres, it’ll help get the pressures right for whatever you are doing!
So try it yourself! If you seriously give it a proper try, and adjust your pressures in the manner it suggests, you’ll get longer life from your tyres, they’ll be less prone to puncturing than otherwise, and they’ll give you traction, road manners, and ride characteristics that not only enhance the life of the tyre, but make it easier on the vehicle and the occupants! Like they say, use the tyre placard to get a good starting point, then fine tune it using the 4psi rule from there. Use the guides suggested pressures for off-road pressures as a start point too, and then do the fine tuning with the 4psi rule. Again, it’ll enhance your driving in more ways than you expect.
One of the first things that I noticed when I started using this rule off road was that when I went driving with others who weren’t aware of the 4psi rule 2 things happened. 1 – they bagged me for stopping and playing with tyre pressures; and 2 – they thought I was a much better driver than the norm because I could go places that they couldn’t without anywhere near the wheelspin or even at all! The only thing that I could see that was different was that I was using the 4psi rule and they were generally not changing pressures much at all! Now that was a long time ago, and it was when people generally worked on HIGH pressures only for off roading, to allow the tyre to cut thru the goop and get down to the firm stuff etc, and since then the whole ballgame has changed and people are much more aware of using lower pressures to enhance traction, but still, it was a telling point at the time.
What about all the variables that impact on optimum tyre pressures?
The thing to remember about the 4psi rule is that it is the ONLY method readily available to all drivers that ACTUALLY takes into account ALL the variables, cos it works off the driving you’ve just done in the last hour or so – ambient temp, air temp, road temp, road surface, driving style, load, tyre carcass, tread construction, etc, etc; BUT it IS retrospective – it’s based on what you’ve just DONE – you hafta make a judgement call on what’s facing you in the next hour, and adjust pressures accordingly!! (but the 4psi rule will let you fine tune that ‘judgement call’ into something quite accurate fairly quickly ) So it is a system that you need to use pretty much all the time until you get a good idea of what variables make how much difference to your pressures, but I’ve noticed with all the people I’ve trained over the years it hasn’t taken anyone all that long to get pretty good at getting their judgement calls pretty close within a few weeks of starting ‘using’ the 4psi rule. So try it, vary your pressures accordingly, and modify your start pressures accordingly, you’ll get better as you go along.
The ‘calculation’ for working out how much to vary your pressures when they are out is just another ‘rule of thumb’, basically if you take 1/2 the difference between what your tyre pressure SHOULD have been and what it ACTUALLY is, and add/subtract accordingly, and you can keep doing that every 30mins/1 hour if you like, but it becomes a tiny adjustment eventually. The suggestion mentioned earlier works too, you just need to be consistant in what methodology you use rather than exact, same with your pressure gauge – the most critical factor is consistency rather than accuracy.
I suppose, anecdotally, this is about the amount my tyres tend to come up from cold starting pressure, to working pressure. Does it work? Dunno, as Doctor Karl says, do the experiment!
80 series brake pad upgrade:
I was browsing this page trying to find where some errant washers went (that old chestnut!), and came across what looks like a nice little brake upgrade for the 80, using 105 series pads.
Was also pleased to note the insides of my hubs looked nothing like this dudes...
Any regulars want part numbers/pads price just holler.
These pics are taken from this couple’s site, of their journey down through Africa in a L322 Range Rover.
I forwarded it to The Accountant, to get him to get that beast out wheeling again!
I read this just mainly out of interest, due to the way DC to DC chargers have become almost de rigeur it seems over here. Whereas I’ve just always charged my ‘second battery’ off y’know, the alternator...
Speaking of the Accountant. He had problem with the battery being flat after a long run on the highway in the L322. Probably the ‘smart’ alternator.
Roaming The Outback:
Sick of overly commercial ‘Overland’ You Tube channels? (I know you are, you hang out here). Let me introduce Brett.
Brett travels Australia whilst his Defender gently sheds parts (just joking mate, if you’re reading), but in all seriousness. I relate to what this guy does more than a lot of people who you feel maybe wouldn’t be into it if You Tube wasn’t around...
If you thought I had a ‘weight problem’.
Here Brett tackles Googs Track as we did last year.
Which, Ronny has just covered to in his latest series. I get the feeling they were pretty much done by then. The schedule of filming takes it’s toll for sure...
I like this guy’s approach.
So, no definitive answer except, we want do document it for ourselves, family, friends and others in that order.
Difficult line to tread for sure.
It looks this is becoming more of a non-negotiable. Anyone have any experience? Advice?
I’ve activated my long dormant instagram account. Not much up there yet, but obviously more to come. I’m starting to get used to being quizzed on our trip from all sorts of people, so this will be a nice easy way to give little updates.
I’m pretty sure I’m following everyone who is on here, who is on there. But if not, hit me up and I’ll check you out. Also if anyone has any good recommendations for accounts to follow?
Trip prep is coming along well. I have a slight feeling of the days clicking by with ever increasing speed. Anyway, I’ll make a proper post around that as time permits.