Simultaneous inflation.deflation of tyres.

[Aussie Jeepster]

Not strictly Discovery related, but with all the discussions I've seen on airing up and airing down, this gadget looks the goods.
INDE FLATE - YouTube (https://www.youtube.com/watch?v=j5EgLVvvbyA)

Indeflate (http://www.4x4community.co.za/shop/index.php?route=product/product&product_id=68)

[Bigbjorn]

Not strictly Discovery related, but with all the discussions I've seen on airing up and airing down, this gadget looks the goods.
INDE FLATE - YouTube (https://www.youtube.com/watch?v=j5EgLVvvbyA)

Indeflate (http://www.4x4community.co.za/shop/index.php?route=product/product&product_id=68)

Find a roadworks site and look at the arrangement on most pneumatic tyre rollers. For decades these have been equipped with a system known as "Air on the Run". The operator can inflate and deflate tyres at will. The plumbing involved would be a bit vulnerable to damage in off road work.

[Tombie]

I’ve watched the video, and I find myself asking.. Why?

What has or hasn’t been gained by this?

[Vern]

I’ve watched the video, and I find myself asking.. Why?

What has or hasn’t been gained by this?Same. How does it differentiate between each tyre? Guessing 2 valves.

[trout1105]

Airing up/down is really no big deal if you have a decent tyre deflator and a good air compressor.
It also gives you the opportunity to check the vehicle for any damage as well [thumbsupbig]

[weeds]

I’ll stick with my stauns, they deflate quick enough for me....they would be close to being the quickest way your deflate 4 tyres.

[Tombie]

I’ll stick with my stauns, they deflate quick enough for me....they would be close to being the quickest way your deflate 4 tyres.

Agreed...

Whilst not condoned when we were staying at Robe for example - I would often fit the Stauns as we left the camp site and just drive along as the tyres deflated. Next stop I would remove and refit the caps.

The unit above seems slower - I need to remove a cap, fit the hose.. go other side, remove cap and fit hose. Return to middle and deflate (approx twice as long as it’s twice the volume.)

Then remove and cap both sides.. and then head to the other end..

With Stauns or equivalent- undo, fit, next wheel; repeat 4 wheels.
By the time I’ve done the lap it’s time to lap again and remove and re-cap...

[TB]

This is similar to another product from the US:
2air/4air/6air Tire Inflator - Deflator (http://www.4crawler.com/4x4/ForSale/4air.shtml)

I've been seriously thinking about getting a 2air. Since somebody asked why, let me explain.

It's really hard to get all your tyres to equal pressure in a hurry if you do them individually, because:
1. When you change the pressure in one tyre you alter the stance of the vehicle and therefore the pressure in every other tyre
2. Tyres are usually cooling down while you're working on them, meaning the first tyre you do will end up lower than the last one (because it continues to drop pressure after you walk away from it)

These differences aren't a big deal front-to-back because we normally need differences there anyway. But side-to-side differences are not nice, especially on the front where it pulls your steering off centre.

If you can connect two tyres on opposite sides with something like this Indeflate or a 2air, the pressure will naturally equalise between them. You can use the centre tap to add or remove air to both tyres at once, and the pressures will end up identical.

The other reason I'd like something like this is because my compressor doesn't have a tank, the only on/off switch is on the compressor, and the pressure gauge and deflator button is on the far end of the hose. So there's always high pressure in the hose while inflating, meaning the gauge isn't telling me what the pressure inside the tyre is. I have to turn off the compressor to get a reading (once the pressure in the hose and in the tyre equalises).

My current tyre inflation routine is to leave the pump on while I inflate all the tyres to an indicated hose pressure above 50psi, turn the pump off, then return to each wheel to check the actual pressure (it's typically about 10psi lower than the hose pressure was) and hopefully lower things down a little.

With a 2air I could connect up a pair of wheels, walk back the compressor, switch it on, wait for the pressure to go high (eg 50psi), switch the compressor off and get a reading right there. Make adjustments up/down as needed. Voila, two wheels done perfectly. Repeat for the other axle.

[Tombie]

Totally disagree....

When you go to air up a vehicle from say 18psi to 36psi and you inflate 1 tyre... the others don’t change at all..
It’s odds on you’re never on a perfectly flat surface either.

If you want it, go for it... it’s just another bit of bulk to add to the vehicle and no serious benefits are derived from it.

[TB]

I have a TPMS in my Disco Sport which shows very clearly the effect that changing one tyre has on all the others. It's because the wheel itself raises or lowers, altering the balance of the vehicle on the suspension, tilting it slightly one way or another. That means different weight distribution on all the wheels, and therefore different pressure than what it was a few moments before.

Is that the only bit you disagree with Tombie, or do you "totally" disagree with the entire post?

[trout1105]

I have a couple of sets of Stauns, One for sand and the other set up for rock pressures.
These are reasonably fast to use but I don't have complete faith in them attaining an accurate tyre pressure so I generally use a tyre deflator that removes the valve so that I get a precise pressure and they are just as fast if not faster than the Stauns to use.
The downside is that you need to carry spare valves in case you bugger one up with these types of devices.

I personally can't see an advantage fitting one of these inflation/deflation devices because it is just something else that can fail and I like to keep the K.I.S.S principle in play when I venture off the bitumen [thumbsupbig]

[TB]

I personally can't see an advantage fitting one of these inflation/deflation devices because it is just something else that can fail

It's not a device, really, and you don't "fit it". It's a portable air hose that connects to two wheels at a time (same axle) with a central manifold that offers you a pressure gauge, a deflation valve and somewhere to hook up your compressor for inflation. The biggest downside is what Tombie pointed out: it's another somewhat bulky thing to carry.

[Tombie]

I disagree because as soon as you get in, the load shifts.
As soon as the fuel starts being consumed the load shifts.
As soon as you park on cambered ground the load shifts.

I’ve run TPMS for years, and never seen a radical shift in balance as tyres are inflated.

More likely volume changes due to cooling of tyres whilst inflating the other side...

[trout1105]

As it usually only takes 5-10 min to air up again I can't see that temperatures of the tyres will alter that much in so short a time.

[TB]

I disagree because as soon as you get in, the load shifts.
As soon as the fuel starts being consumed the load shifts.
As soon as you park on cambered ground the load shifts.

I’ve run TPMS for years, and never seen a radical shift in balance as tyres are inflated.

More likely volume changes due to cooling of tyres whilst inflating the other side...

All fair comments, but I didn't say "radical" (I don't think I did... nail me if I'm mistaken about that!) and I also listed cooling as a reason for ending up with different pressures when working on one tyre at a time.

Doing both tyres on an axle simultaneously with equalised pressure eliminates two sources of difference. That's the point of these kinds of things. Whether they're worthwhile overall is pretty much an individual decision – everybody weighs up the pros and cons according to their personal priorities.

I haven't decided to get one. It's just something I've been mulling over.

[Tombie]

As it usually only takes 5-10 min to air up again I can't see that temperatures of the tyres will alter that much in so short a time.

You’d be surprised... if you have a temp gun give it a go...

[TB]

As it usually only takes 5-10 min to air up again I can't see that temperatures of the tyres will alter that much in so short a time.

Rate of temperature change is proportional to the 4th power of the temperature difference, meaning that things go from really hot to kinda hot way faster than they go from kinda hot to just warm.

Gas pressure is directly proportional to temperature, so the pressure follows the same downwards curve as temperature. Fast drop initially, slowing down as it goes.

I've got a fast compressor and it plugs straight onto the Anderson near my tow hitch. So I can be airing up the first tyre within 30 seconds of pulling over, while that tyre is still really hot. All the tyres are rapidly cooling at this point.

By the time I get to the fourth tyre, it's temperature/pressure will be a lot lower than the first tyre was when I started. I can get it up to the same pressure as made the first tyre, but by this time the first tyre will also have dropped down the steepest part of the curve and is now at a lower pressure than what I'm about to make the fourth tyre.

But hey, we all get by with a bit of experience and judgement and most of our wheels don't fall off. This is not to say there's a problem and everybody needs to start doing something different, it's just explaining why there's some physical reasons that airing two tyres simultaneously has some technical benefits. Are they worth it? Up to you.

[trout1105]

You’d be surprised... if you have a temp gun give it a go...

I am thinking that the cooler air that is being added to the tyre when airing up would have more of an effect on the temperature/pressure of the air in the tyre than the amount of heat being radiated off the outside of the tyre.
I could be wrong ( It's not that odd an occurrence ) But that's the way I see it.

[Tombie]

Air from a portable 4wd compressor is significantly hot...
Hence why pressure should be checked again later.

[weeds]

I still reckon my stain would beat the systems where you remove the valve....and way less kneeling down...the added benefit is what Tombie pointed out, you can be airing down while driving (it helped me on once when I misjudged some soft sand). Re: accuracy when I’m losing pressures I’m off road....if it within 1-2psi I’m happy with that.

Re-inflating, happy to take my time and generally the tyres would be much above ambient temps.

[gusthedog]

All fair comments, but I didn't say "radical" (I don't think I did... nail me if I'm mistaken about that!) and I also listed cooling as a reason for ending up with different pressures when working on one tyre at a time.

Doing both tyres on an axle simultaneously with equalised pressure eliminates two sources of difference. That's the point of these kinds of things. Whether they're worthwhile overall is pretty much an individual decision – everybody weighs up the pros and cons according to their personal priorities.

I haven't decided to get one. It's just something I've been mulling over.Not if one tyre is in the sun and the other in the shade. The one in the sun will not cool down as fast as the one in the shade.

Also if you aren't on perfectly level ground, there will be slightly more load on one tyre anyway. However, the load on the tyre doesn't dramatically change the pressure.

Anyway even if there is a difference between tyres it's not going to be huge doing it the normal way. Just say its 2psi difference doing it tyre by tyre. Who cares? It will hardly make a difference off road. I think you are over complicating something that doesn't need it. Of course happy to be proven wrong [emoji14]

[TB]

Not if one tyre is in the sun and the other in the shade. The one in the sun will not cool down as fast as the one in the shade.

True. Not sure how big an effect that is though. It's also variable and somewhat controllable, so not something which you have to think about every time you air up.


Also if you aren't on perfectly level ground, there will be slightly more load on one tyre anyway. However, the load on the tyre doesn't dramatically change the pressure.

Pressure = force divided by area. You add weight (which because of gravity increases the force), you increase the pressure between the ground and the contact area of the tyre, which in turn increases the internal air pressure. The tyre, being elastic, will expand a bit, which allows it to squash down onto the ground a bit, increasing the area and so decreasing the pressure slightly. But being elastic is like being a spring – the more it's stretched the harder it resists. So the net result is that the extra weight does make tyre pressure increase up until the point where your rims are squished to the ground or the tyre pops.


Anyway even if there is a difference between tyres it's not going to be huge doing it the normal way. Just say its 2psi difference doing it tyre by tyre. Who cares? It will hardly make a difference off road.

Agreed. But I don't air up to go off road, I air up when I'm getting back onto the bitumen. At 110kph on the blacktop a couple of PSI is more noticeable.


I think you are over complicating something that doesn't need it.

Every real thing is complicated when you look closely. That just means it's interesting. Doesn't mean everybody needs to change the way they're dealing with their tyre pressures.


Of course happy to be proven wrong [emoji14]

I think we are in agreement that it's not a big deal. But I still wonder whether I might personally prefer doing my tyres with one of these things compared to what I'm doing now.

[ATH]

Gawd! Before reading this thread I never realised how complicated airing up/down was. Now I won't sleep tonight as I lay there trying to figure out if I've been doing it wrong all these past 25 years or so. :-)
AlanH.

[DiscoJeffster]

Gawd! Before reading this thread I never realised how complicated airing up/down was. Now I won't sleep tonight as I lay there trying to figure out if I've been doing it wrong all these past 25 years or so. :-)
AlanH.

There are no better places to over complicate something than Internet forums [emoji23]

[trout1105]

Gawd! Before reading this thread I never realised how complicated airing up/down was. Now I won't sleep tonight as I lay there trying to figure out if I've been doing it wrong all these past 25 years or so. :-)
AlanH.

Don't sweat it Mate as most of us older Farts don't know nuthin , Apparently [bigwhistle][biggrin]

[jh972]

30 psi in your tyre. Jack the car up. Still 30 psi in the tyre. The stance will have no effect.....

[donh54]

So, driving south down the Bruce highway, for example, in the morning your car will have more pressure on the left side, and in the afternoon, more on the right side? Should I stop at lunch time and adjust tyre pressures?

[techron]

I think there are more variations in pressure readings of tyre gauges anyway so all this does is to equalise pressures a little bit more accurately side to side than you can generally achieve by reading a gauge. Most pressures we set for different terrain are those that work for us from experience.
I once had to return a well known make of gauge as it was more than 6 psi out. So, for me, chasing this marginal perceived difference side to side is irrelevant compared to all the other variable pressure factors?
Cheers, techron[smilebigeye]

[crash]

One of my mates made up a similar device for airing up. Works a treat - but he has an onboard air sytem that is very quick.
I would think you would need a fairly good compressor with a fair cfm for it to be effective.

Does it save any time VS doing each wheel individually - maybe a bit?

How much difference would 10mm air hose VS 8mm VS 6mm would make in inflation times.
Only you can decide if it is worth it or not.

For deflating I have a cheap triggered air hose with a gauge attached - pull the trigger deflate - stop and check pressure on gauge.

[TB]

30 psi in your tyre. Jack the car up. Still 30 psi in the tyre. The stance will have no effect.....

Technically, I don't think that's correct. For practical purposes, on a given vehicle/wheel/tyre combo, the effect could be negligible. Neither of us should fret about it either way.

[TB]

So, driving south down the Bruce highway, for example, in the morning your car will have more pressure on the left side, and in the afternoon, more on the right side? Should I stop at lunch time and adjust tyre pressures?

If you're implying that it's a silly idea, I agree with you.

The solar heating aspect of this is a distraction. Compared to the heat generated by rolling friction, I think it's probably negligible. But technically, if you had uneven tyre pressures to begin with and then drove with the higher pressure side facing the sun, the sun would make the imbalance that tiny bit worse.

Come on guys, nobody's saying you've been doing it wrong. People are just tinkering with ideas for making things better, if possible. There are some technical reasons why airing 2 or 4 tyres at a time can result in more even pressure distribution than doing them one at a time. At the same time, I keep saying it isn't a big deal...

[Aussie Jeepster]

Wow, as the one who started this thread, I had no idea it would go this far!!
It's all rather academic as the South Africans don't ship OS (or not without a lot of stuffing around)
And I just tried reading the US website, and got lost and lost interest!!!! I'm currently in the US and have emailed the maker to see what I can find out.
Thanks for everyone's input.

[crash]

It's all rather academic as the South Africans don't ship OS (or not without a lot of stuffing around)
And I just tried reading the US website, and got lost and lost interest!!!! I'm currently in the US and have emailed the maker to see what I can find out.
Thanks for everyone's input.
Why don't you make your own?
The most expensive part would be the gauge, and you could use a ball valve for the air release with a male quick connect on it to connect to the compressor.
You buy everything you need from a hardware shop.

[Aussie Jeepster]

Why don't you make your own?
The most expensive part would be the gauge, and you could use a ball valve for the air release with a male quick connect on it to connect to the compressor.
You buy everything you need from a hardware shop.

I woke up this morning and thought exactly the same thing!
There is no rocket science involved, and I've got all the bits back home in Adelaide.

[Tombie]

Certainly wouldn’t be difficult.