The last time, I spoke on my experience with a deflated tire during my first visit to my state. I highlighted reasons why choosing either of  [Nitrogen and Compressed air](https://steemit.com/stemng/@mrbreeziewrites/nitrogen-vs-air-the-concept-of-automobile-tire-inflation) could be the best gas for your tires. I also mentioned reasons why a tire could get deflated. I mentioned that it could either be through a Leak, Permeation or through temperature changes. 

But, wouldn't it better if we could be saved from the stress of having to do manual inflation of our tires? Or monitoring the tires for a drop in pressure?

Well, I would appreciate that and I'm certain you would too. So, permit me to introduce you to the savior - SIT!

I'm definitely not commanding you to put your ass down but rather I'm introducing to you the Self Inflating Tire technology! The savior from the manual Tire inflation stress.

It is worth noting that the SIT technology doesn't just help inflate our tires but along with some sensing controls, it helps to monitor and regulate the Tire pressure and hence ensures the safe, efficient and ideal working of tires.

First, before we proceed, I'll like to tell us the effects of having an **overinflated or underinflated tire**. We all know that anything operated in a state that is different from the normal or accepted way leads to a problem or two, so, running tires on overinflated or underinflated state could hamper its efficiency and lifespan.

A survey conducted on why about 200-300 people die due to road accident every day in India by [Apollo Tyres](https://www.onlinejournal.in/IJIRV3I3/240.pdf), the found out that 75% of the cars are not driven on the correct and recommended tire pressure level. They found out that 44% were overinflated while 34% were underinflated.

For **overinflation**, the efficiency of the tire decreases and it becomes susceptible to bursting at high speed which either results in a collision or more complex accidents. **Underinflation**, on the other hand, affects the grip of the tire to the ground, it affects wheel handling and most times, it leads to quicker overheating of the tires and wearing off of the tire treads.

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**So, how does the SIT technology come in here?**

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**Self Inflating Tire technology** brings more than just machine enabled inflation aid, it brings about on-road safety, maintenance cost reduction, longer tire lifespan and of course efficient operation of the tires. The fact that we can't tell by just looking if a tire's pressure has gone below the recommended makes SIT a significant technology. 

Through normal driving, car tires lose air when it hit pot-holes, through permeation or during temperature changes. During winter, tires can lose about 2PSI due to temperature changes. So, the need for a system that not only helps inflate the tires but also monitors pressure changes automatically becomes important.

<center>![Tire](https://upload.wikimedia.org/wikipedia/commons/thumb/b/bf/CTIS.jpg/800px-CTIS.jpg)</center>
<center><sub>[wikimedia CCO: CTIS](https://commons.wikimedia.org/wiki/File:CTIS.jpg)</sub></center><br/>

<hr/>

**What's the SIT technology?**

<hr/>

Self Inflating Tire technology is based on three principles - *DNI* which means; **Detect, Notify and Inflate**.  Through the sensors enabled system, drop in tire pressure is detected and it Notifies the driver by passing the information through an electrical signal enabled by the **Electrical control unit (ECU)** and the message is relayed to the mechanical system, usually a **Pneumatic Control Unit (PCU)** which then inflate back the tires to the specified level.

The SIT system is a combination of an Electrical and Electronics unit and the Mechanical units that work together to help monitor the tire pressure level. It is specifically designed to help maintain tire pressure drop in cases of leakages, permeation, and environmental condition changes. 

In recent years, the technology has seen wide application in different tire pressure regulating systems. It is being used in systems like the Central Tire Inflation System (CTIS), the Tire Maintenance System (TMS), AIRGO system, Meritor Tire Inflation System (MTIS) etc. This technology is widely used in the Military and Sports industry where there isn't much time for self-monitoring of tire pressure and manual inflation.

<hr/>

**What are the Major parts of a SIT system and how does the technology work?**

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**Major Parts**

As said, there are many designs existing for the SIT technology, but the basic parts of the SIT are same as they use the same principle - the DNI. The ECU is charged with the responsibility of monitoring the pressure level through sensors and then relaying the information to the PCU - the Mechanical unit which returns the tire to the required level. 

For all kinds of SIT systems, there are usually; 

+ A Valve opening
+ Central Sensors
+ An Air source
+ A duct network for Air Transmission 
+ A Pressure relief Vent,

The **Valve** is needed to control airflow in the system. As one tire is being inflated, others must be closed. This is possible through valve opening and closing interchanging for each tire during inflation (or deflation in case of overinflation).

The **Central Sensor** as the name implies is the combination of sensors responsible for monitoring and detecting pressure changes during working of the system.It detects any changes and passes it to the Mechanical unit through electrical signals to the driver for action.

The **Air source** is the major backbone of the system. It is where the tire gets the gas that is being filled in whenever there's a deflation. Usually, it is from an existing air system in the vehicle say the braking or pneumatic system. The source after receiving a signal from the sensor supplies the needed volume of gas to the tire through ducting that has been installed for this purpose.

For transmitting the gas to the tire, there exists a hose or hollow hub (ducting) through which this air passes to the valve installed for the tire. **A sealed hub axle** which acts as a conduit is usually used for this purpose for its proximity to the tire.

The last but equally important part is a **Pressure Relief Vent** that acts as an exhaust for some excess gas so as to prevent the hub from damage.

**How does the SIT technology work?**

The system integrates an Electrical and Electronic system with a Mechanical unit to execute its functions. The Air source supplies the gas and the Pneumatic system usually a compressor compresses the ga to a level usable by the tire. The compressed gas is then transferred to an Air tank that stores it. When the tires are in operation, the Central sensors are actively monitoring the pressure level. If any reduction or overinflation is detected, the sensors send an electrical signal to the PCU, this sends a signal to the driver for initiating the process. 

The signal reaches the air tank that pumps the needed gas using a reciprocating motion of the pneumatic system through the ducting to the wheel axles and then the tire valves. The Inflation is done in turns for each tire till a pre-set pressure standard for the tires is achieved in all of them. The sensor trips of the supply and the monitoring begin all over.

<hr/>

**Major Applications and Benefits of the SIT Technology**

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**Major areas of Application**

As we must notice, SIT technology helps take the stress of checking for tire pressure and the process of manual inflation. We may argue that does it really worth the cash? But, we might change our mind if we consider its application in areas of emergency and criticality. The major area where the technology includes the Military vehicles, Emergency Vehicles, Sports cars and interstate commercial vehicles.<br>

<div class="pull-left"><center><img src="https://upload.wikimedia.org/wikipedia/commons/thumb/2/24/URAL-375D_pic1.JPG/640px-URAL-375D_pic1.JPG" /><br/><br/><sup><sup><a href="https://ja.wikipedia.org/wiki/%E3%83%95%E3%82%A1%E3%82%A4%E3%83%AB:URAL-375D_pic1.JPG">Wikimedia Creative Common: URAL-375D pic1 -Military Truck</a></sup></sup></center></div><strong>The Military vehicles</strong> have been one of the prominent areas of SIT application. The PMS is usually found in almost all the military trucks. They help them regulate the tire pressure level to avoid any kind of tire deflation during action or an intervention mission.
<br><br>Here, if there wasn't such technology, it could be life-threatening for the military guys to have stop-overs doing manual inflation.
<br><br><br><br>
<div class="pull-left"><center><img src="https://upload.wikimedia.org/wikipedia/en/a/a7/QAS-ambulance.png" /><br/><br/><sup><sup><a href="https://en.wikipedia.org/wiki/File:QAS-ambulance.png">Wikimedia Creative Common: QAS-ambulance</a></sup></sup></center></div>In Emergency vehicles like Ambulances, fire vehicles or Police vehicles, the SIT technology is very significant for it could prove life-saving. <br><br>The self-inflating tech of the tires makes them less worried about the level of the tires in case an emergency comes up.<br><br><br><br><br>

<div class="pull-left"><center><img src="https://cdn.pixabay.com/photo/2017/03/05/15/29/aston-2118857_640.jpg" /><br/><br/><sup><sup><a href="https://pixabay.com/en/aston-martin-sports-car-auto-2118857/">Pixabay - CC0 Creative Commons: Sport Car</a></sup></sup></center></div><strong>Racing cars</strong> use the SIT technology extensively as it helps them maintain balance and controlled speed through tire pressure regulation of the technology. <br><br>Under-inflated tires make it hard for the driver to have full control of the grip of the tires to the ground and could affect steering.<br><br><br><br>

<div class="pull-left"><center><img src="https://cdn.pixabay.com/photo/2017/08/11/19/36/vw-2632486_640.png" /><br/><br/><sup><sup><a href="https://pixabay.com/en/vw-bulli-camping-bus-vw-bulli-2632486/">Pixabay - CC0 Creative Commons: Van</a></sup></sup></center></div><strong>Long distance traveling commercial buses</strong> can also benefit from the technology. As said earlier, about 75% of road accidents occur due to tire air pressure level.<br><br>So, this technology could prove life-saving and eliminate time wastage of finding means of inflating tires in the middle of the journey (as in my case <a href="https://steemit.com/stemng/@mrbreeziewrites/nitrogen-vs-air-the-concept-of-automobile-tire-inflation">here</a>).
<br><br><br><br>

**Benefits of  the SIT Technology**

Many benefits come with integrating the SIT technology into the vehicles. Beyond stress relief, it is a life-saving and cost-effective technology. It could be beneficial to both the driver improving it and the manufacturer as well. For the drivers, 
* It ensures Safety
* It helps improve fuel efficiency
* It ensures tire longevity
* It ensures convenience and gives assurance.

For Manufacturers;

* It gives a Competitive edge over others not producing such
* It gives them a higher profit margin
* It differentiates them from others for their added value services.


#### CONCLUSION<br><br>

The SIT Technology ensures that heavy truck and bad road have less effect on dropping the tire pressure as it gets automatically reinstated if reduced. So, we can conclude that the technology of SIT is significant and can really save life, time and cost.

What do you think about it? Did you SIT while reading?

Thanks for your audience.

### REFERENCES

+ Kamlesh R. P, Gufran I. S., and Swapnil H. K., 2017. "Self-Inflating Tyre System". Imperial Journal of Interdisciplinary Research (IJIR), Vol-3, Issue-3, 2017. ISSN: 2454-1362, http://www.onlinejournal.in

+ Vishnuram. K, Dinesh.R, Suresh K. .N, Deepan K. S. and Tamil C., 2015."Self Inflating Tyres". International Journal on Applications in Mechanical and Production Engineering, Volume 1: Issue 5: May 2015, pp 5-6. ISSN ( online): 2395-3500, www.aetsjournal.com

+ Lee Ann Obringer, "How Self-inflating Tires Work". https://auto.howstuffworks.com/self-inflating-tire.htm/printable

+ [SIT - Self Inflating Tire](http://www.selfinflatingtire.com/)


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