I have a Prado 4x4 with BFG All Terrain Tyres fitted running with 40psi all round and towing the den, 1000kg with 90kg on the tow ball, the tug fully loaded would probably have around 100kg approx in the back. I run with the 40psi when nothing in or on the back as well. I am aware of the lower pressures if on sand etc.
I was involved in a discussion today with non GN members but GN's. They reckon I am running with too higher pressure.
Question is I spose, what do you run with??
-- Edited by Dougwe on Thursday 8th of May 2014 07:01:22 PM
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Have you tried the "4 PSI" rule for setting up your tyre pressures when running on the tar seal.Think you will find the info if you do a search. This has come up a few times on here over the years.
SEARCH for "Tyre Pressures" one started by Garry Kelly in 2008 has a good deal of info and debate.
I reduce my tyre pressures all round (van included) when driving for long periods on unsealed roads. I find it gives a better ride reducing the shock of corrugations and loose gravel / stone impact on the tread. This is a chart I use for reference, keeping it with the tyre Gauge.
SURFACE CONDITIONS - PRESSURE REDUCTION
Sealed surface 100% = your recommended sealed road pressure.
Gravel / Corrugations Reduce by 10 15%
Rocks, Reduce by 15 20%
Mud, Reduce by 25%
Sand, Reduce by 50 60%
-- Edited by elliemike on Thursday 8th of May 2014 07:21:02 PM
Doug I had a 2003 Prado for 8yrs and ran B/Stone A/Ts and kept same pressures as you all the time.All good and never a problem.I just rotated them every 10 Ks .John
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My first suggestion would be to check Toyota's recommendations - either in the Owner's Manual or on the vehicle's placard (usually inside the driver's door - on the door itself or the door surround).
As a bit of background, vehicle manufacturers tend to recommend a tyre pressure that will give a "soft and comfortable ride". Tyre manufacturers tend to recommend a tyre pressure that will provide good road-holding and wear. Often the best pressure is somewhere inbetween.
My rule of thumb for the past 40 odd years (and there are times when I have indeed been odd ) is to run my tyres at about 4 to 6 PSI above the vehicle manufacturer's recommendation. For example, if they recommend 28PSI for the tyre I would run mine at 32 to 34PSI.
Having then decided the pressure to run - which I usually do at the time I begin ownership of the vehicle - I see how it feels on the road and how it wears. I check my tyres usually weekly - but definitely each 500km or so. If there is no appreciable 'unwanted' wear showing then I assume the pressure is satisfactory. It usually is.
This pic gives an indication of how to see what the 'wear pattern' is likely to be -
The pic shows the wear well-advanced.
Given you can see the "pattern" of wear as it progresses, this is what I look for each 500km or so. If outside edges show wear signs - up the pressure by maybe 2PSI. If the centre is beginning to show signs of wear, lower by 2PSI.
However, you have had the Prado for a fair time now - bit late to begin fluffing around with the above. So, check your tyres and see if they are showing any adverse signs of wear. If they look like the middle tyre in the pic - continue to do what you are doing ... but still refer to the recommendations by Toyota.
Now - with my Discovery, when not towing I run 34PSI all round which seems to give me the best road-holding and wear. If I do a bit of bush-bashing on un-sealed roads I drop them to 28PSI. Sand and steep serious 4X4 conditions will mean differing pressures.
When towing I put 36PSI in the front and 44PSI in the rear. (Land Rover recommend 34PSI and 42PSI when towing). I have found "my" pressures show the best wear pattern.
The "4-PSI Rule" above is a bit of a 'rule of thumb' - but it is not too accurate because there are so many variables that can affect its accuracy. For example, cold ambient temp in the morning when you check pressures but the day gets a warmer ambient will, in itself, affect the pressures the tyre builds up to. I have gone on too long already, so I will leave it at that as there again so many variables.
Bottom line - Check how your tyres are wearing at the moment at the pressures you are running now ... if they look good I wouldn't worry.
However, I do think it is wise to have a slightly lower pressure in the front compared to the rear when towing - this helps to restore some of the 'inbuilt understeer' of the vehicle and makes the whole rig more stable, particularly when cornering. Therefore, when towing, I would drop the pressures in your Prado to maybe 36PSI front and 40PSI rear when towing. Perhaps 34PSI all round when not towing. But, again, as I said, if they are wearing evenly and well at the moment, leave them alone.
Sorry for being so long-winded, but this can be a complex issue - and is completely dependent on type of vehicle, type of tyre, road conditions driven on, speeds usually driven at, etc etc etc.
Cheers - John
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Doug I think you are running about the right pressures.
A way to ascertain this in my experience is this:
If pressures are too low you will feel the side movement of the vehicle especially the rear wheels,,, ie a small sway, side to side. Also possible "sloppy" steering effect.
If too tight you will feel a rough ride and every bump,, within reason of course.
Our Landcruiser 79 series ute runs 60 PSI in the rear and 40 PSI in the front,, why?
The front axle weight is normal Toyota weight. HOWEVER the rear axle is 2.3 tonnes (we had have uprated GVM to 3.7 tonnes) with van on and loaded. IF WE RUN REAR TYRES AT 50 PSI you can feel the excessive sway, 55PSI is slightly better BUT 60 PSI IS IDEAL.
We got 60,000 km + on 6 Coopers tyre with even wear on tread (except 2 in the Adelaide hills for 12 months or so).
Stick with what you are comfortable and by all means watch the tread wear,,, but this is retrospective action and not pro active IMHO.
Many tell me I'm running rear tyre pressures too high without even asking why or the load on the axle,,, silly eh!
Hope this explains it.
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Doug on my door placard for my mazda bt50 it reads front and back 35/35 road running 38/38 enco and full load 38/44 psi and i follow that and my size tyres 255/70/16 bridgestone HT.
I also thought I read some where that the 4psi rule was for passenger car tyres and 4x4 tyres was 6psi but I could be wrong.
AS a matter of interest (to some anyway) we had Tyredogs fitted to rear tyre of tug 265X70 R16's and van 215X75 R15 (I think - too cold to go outside),,,,
pressures rose about 7-8PSI on tug on hot days and 5-6PSI on van on warm/hot days
just some info
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RockyLizard's rather long post has the best information on this topic.
Tyre contact area on the road is the most important issue with regard to safety, and the resultant wear pattern indicates if you have it right or not.
To be proactive and not have to wait until the tyres show wear, you can do a simple chalk test.
Find a nice quiet stretch of flat sealed road.
Make a 20mm wide mark across the full width of the tyres with a stick of chalk.
Drive about 50 - 100 metres down the road, stop and check the chalk marks.
Mark worn off evenly across the tyre - pressure correct.
Mark worn off on outside edges but still there in the middle - tyre under inflated.
Mark still there on the outside edges but worn off in the middle - tyre over inflated.
Couple of other points, within reasonable limits -
Tyres too soft use extra fuel, but give a better ride on rough surfaces.
Tyres too hard give better fuel economy, but the rough ride shakes sh*t out of the suspension.
PJK
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Thanks everyone for the input. It was just a discussion with fellow GN's but got me thinking.
I started out with 32psi and gradually built up to the current 40psi. I have been very happy with the results so far so I think I will keep on keeping on as is and adjust as required for different conditions.
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TUG.......2014 Holden LT Colorado Twin Cab Ute with Canopy
DEN....... 2014 "Chief" Arrow CV (with some changes)
Decent tyres have the maximum tyre pressures to use stamped on them, we use them as a guide and normally run 5-10% above or below that, depending on what we are doing. Our cruisers run 45psi, you can tell by the wear pattern as to how it is working and we tend to get very long distances out of our tyres. Always have a good laugh when see those who drop their tyre pressures when on dirt, it's great advertising to shorten tyre life, as tyre walls deteriorate rapidly when under pressure with warped side walls and banging up and down on corrugations. They are designed to operate under pressures which keep as much weight off the walls as possible and keep the tyre in its best configuration, not add weight and twist to it.
Only time we've dropped our tyre pressures, is in sand and then it's only 10psi to flatten the tread pattern and give us a wider grip on the sand.
The plaque usually on drivers door gives recommended tyre pressure for the tyres that were originally fitted to the vehicle i gave been told by tyre retailers there are different pressures required for different brands and types of tyres. last ran Coopers a/t now running Pirelli Scorpion a/t .
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Dropping tyre pressure on dirt roads is mainly to reduce damage from the odd stray large rock you may encounter. On very rough dirt/rocky tracks it is a good idea to drop the tyre pressure considerably to allow the tyre to ride over sharp edges with lesser chance of damaging tyres. How far you drop the pressure depends on many things, including: number of wall plies, how rough the track is and what sort of speed you are doing, vehicle weight/loading. As stated previously, running tyres under inflated can cause premature wear to side walls and outer tread face. Running tyres over inflated can cause lack of grip and steering response, and prematurely wear the centre of the tread face.
My Troopy with Mickey Thompsons STZ Baja's I normally run at 40psi front, 36psi rear unladen. Up the rear to 40psi when towing the small Avan. On dirt tracks I'll drop all tyres to 36psi unladen, and down to 32 with chunky rocks on the road. On sand down to 20psi all round.
On my old 4Runner fitted with BFG's I had to drop the tyres down to 15psi on the sand due to the stiffer walls.
YES Keep in mind under low tyre pressure conditions.. Limit your speed as the tyre flex due to lower pressures create heat..
Which can lead to tyre delaminating. Not that you would be going too quick in these conditions!!
Common sense but unfortunately NOT very common..
Wonder how many who claim they drop their tyre pressures when getting off bitumen have ever lived outside a city.
Think about it, how many times do you see people living in the bush stop when they get off the bitumen and reduce their tyre pressures, or the other way round. Having spent the majority of my life in the bush, never known any bushie who lowers tyres pressures. The majority use tyre pressure well above what urban people do. We run our road car tyres at 45psi, with light truck tyres, they are always 5-10% over the stated pressures on the tyre walls, same with the bus and never seen a road train or truckie drop tyre pressure when going from bitumen to dirt. Who has got 10-15 minutes to waste aiding tyre manufactures profit growth, not me. As soon as you drop the pressure, the tyre walls bow and tend to de-laminate over time especially if you are carrying any weight, which will effect the tyre wall and tread configuration dramatically.
-- Edited by native pepper on Sunday 18th of May 2014 09:37:00 AM
Depends on the dirt road NP, there is 145km of dirt road I've travelled half a dozen times at over 100KPH with 40psi in tyres.. but it was a hard packed freshly graded sand/clay mix road, and dry. It was as good as any highway you'd travel. And there are rough tracks where sharp edged gibbers protrude through the surface that do require dropping the pressure and your speed, if you want to save your tyres from being torn to shreds. Also on corrugated dirt roads you have to find that "sweet" speed that flattens out the corrugations, but also allows safe driving depending on the surface type.
) is to run my tyres at about 4 to 6 PSI above the vehicle manufacturer's recommendation. For example, if they recommend 28PSI for the tyre I would run mine at 32 to 34PSI.
