Tire pressure

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GeoCampers #4771

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Came across this pice of valuable information on a FB page and thought I share it with all of you.
Don't know how correct this is, but to me it seems legit.

"First of all, this is a smart question. Many "experts" out there are getting stuck because they have no fuckin idea what they are doing.

A correct pressure has to be calculated according the tires you have. for the following examples, I'll assume you have BFG KO2. Engraved on the tire sidewall, you see the max load, e.g. 1250kg, also to be taken from the LI (e.g. 116) and a table, which is only valid at max pressure of e.g. 550kPa (5,5bar) for a KO2. to be correct, you should have a scale and get the proper axle weights of your car. let's assume you have a 50\50 weight distribution front\back, that will result in a wheel load of 750kg with your 3000kg overall weight. your tire can take 1250kg at 5,5 bar...it's a linear function, half pressure, half load bearing capacity. 2,75bar would give you 625kg in this example. you got the point? so 5,5bar\1250kg = x bar\750kg which gives you an x= 3,3bar.

This is you road pressure. Reduce by 25% for high speed off-road tracks up to 90km\h, 50% for off road driving up to 50km\h, reduce down to 1bar for dunes and with high caution down to 0,8bar for self recovery. If you have bead lock rims, you can go down to 0,5 bar.

Tire temperature is a great indicator to monitor tire health. If you go too fast for too long with too less pressure, your tire will overheat and eventually fail. Test: hold the back of your hand against the sidewall. If it's warm, all good. If it's hot, be cautious, go slower or increase tire pressure. If it's HOT (like a fresh cup of coffee hot) then it's too much, definitely increase pressure or slow down."
 

Billiebob

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Not bad, not the bible but lots of truth there. Definitely if your overlander is fully loaded, maybe even over GVWR, I'd say you should not be airing down but yes, read the load rating at what pressure off the tire, scale the axle and see if you need full air pressure or have room to air down.

On the other end that F350 Dually when running empty can likely air down lots, even on the highway, to smooth the ride.
 
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Constantin

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Very interesting. Tanks @Toon for the input.
By using common sense and knowing the important stuff about my weight including the load as well as terrain and speed and also not being too “shy” deflating and inflating again every time conditions change I’ve never had issues so far. Always considering the own type of tires.
 

Theovdw

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Very interesting info, thanks!
Just checked it with my BF KO2 tyres and this method indicates a higher pressure as in the car manual.
I already thougt that the tires seemed a bit under pressure with that value.
For the correct weight a visit to our local recycle parc is always handy . Just the load distribution per axle will be a guestimate..
 

Laurensvh

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Hmm.. very interesting. I think i need to air up a bit for road use then :p Never really did the calculation or gave it any real thought.
Also once read something about the shape of the tire, that an offroad or allterrain tire isnt really flat schaped. This would be that for on road the side doesnt 100% touch the ground (at a high enough tire pressure). When offroad it would flatten out. Anyone hear of this?
 

Robert OB 33/48

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Same, thanks Toon. As I now figured out, I am good with my tire pressure.
I knew more or less these numbers, but not why. That is changed now.
Many thanks.
 

MazeVX

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Hmm I wouldn't call it wrong but it's not entirely right, the width of the rim together with some other things is also a important factor.
It's overall extremely simplified and I wouldn't trust it. Calculation of tire pressure is a complicated thing.

The are several practical methods explained overall but I guess it gives you a direction if you have nothing else to start with.
 

NotGumby

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Thanks Toon. Good information. I've got a Tire Pressure guide from Cooper. Combined with this I may be able to nail it down closer.
 

GeoCampers #4771

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Thanks Toon. Good information. I've got a Tire Pressure guide from Cooper. Combined with this I may be able to nail it down closer.
Rik, can you share the tire presure guide from Cooper? sounds intresting. thx
 

NotGumby

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