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-   -   Direct vs Indirect TPMS | Which one does your car have? (https://www.team-bhp.com/forum/tyre-alloy-wheel-section/252724-direct-vs-indirect-tpms-one-does-your-car-have.html)

A Tyre Pressure Monitoring System, or TPMS, is possibly one of the most understated yet very crucial safety feature for a two/four wheeler.

For the uninitiated, the TPMS is defined as “a system fitted on a vehicle, able to perform a function to evaluate the inflation pressure of the tyres or the variation of this inflation pressure over time and to transmit corresponding information to the user while the vehicle is running”.

Through this thread and the associated poll, the intention is to gather views about your experiences regarding usage of TPMS so that the wider audience gets to understand and ultimately use it for improving their own safety.

Personally, even though I was aware about TPMS, I saw it used in mainstream only about 3-4 years ago when I started seeing folks buying external tyre sensors. However, now that I have a car which has an in-built TPMS, this has made me aware of its importance explicitly.

In this thread/poll, firstly, I have tried to call out certain merits of having this feature. Then, have tried to distinguish between the various categories.

So, here goes..

The dynamic behavior of a pneumatic tyre is closely connected to its inflation pressure. Key factors like braking distance and lateral stability require the inflation pressures to be adjusted and kept as specified by the vehicle manufacturer. Extreme under-inflation can even lead to thermal and mechanical overload caused by overheating and subsequent, sudden destruction of the tyre itself. Additionally, fuel efficiency and tyre wear are severely affected by under-inflation. Tyres do not only leak air if punctured, they also leak air naturally, and over a year, even a typical new, properly mounted tyre can lose from 2 to 10 psi, roughly 10% or even more of its initial pressure.

Some no-brainer advantages of having a TPMS:-

• Fuel savings: According to the GITI (S’pore based company), for every 10% of under-inflation on each tyre on a vehicle, a 1% reduction in fuel economy will occur. In the United States alone, the Department of Transportation estimates that under inflated tyres waste 2 billion US gallons of fuel each year.

• Extended tyre life: Under inflated tyres are the number one cause of tyre failure and contribute to tyre disintegration, heat buildup, ply separation and sidewall/casing breakdowns. Moreover, running a tyre even briefly on inadequate pressure breaks down the casing and prevents the ability to retread.

• Improved safety: Under-inflated tyres lead to tread separation and tyre failure, resulting in thousands of accidents, injuries and deaths per year. Further, tyres properly inflated add greater stability, handling and braking efficiencies and provide greater safety for the driver, the vehicle, the loads and others on the road.

• Environmental efficiency: Under-inflated tyres, as estimated by the US Department of Transportation, release over 26 billion kilograms (57.5 billion pounds) of unnecessary carbon-monoxide pollutants into the atmosphere each year in the United States alone.

Further statistics include:-

• The French Sécurité Routière, a road safety organization, estimates that 9% of all road accidents involving fatalities are attributable to tyre under-inflation, and the German DEKRA, a product safety organization, estimated that 41% of accidents with physical injuries are linked to tyre problems.
  The European Union reports that an average under-inflation of 40 kPa produces an increase of fuel consumption of 2% and a decrease of tyre life of 25%. The European Union concludes that tyre under-inflation today is responsible for over 20 million liters of unnecessarily-burned fuel, dumping over 2 million tonnes of CO2 into the atmosphere, and for 200 million tyres being prematurely wasted worldwide.

Now onto the different types of TPMS:

• iTPMS or Indirect TPMS: Indirectly measuring, software-based systems, which by evaluating and combining existing sensor signals like wheel speeds, accelerometers, driveline data, etc. estimate and monitor the tyre pressure without physical pressure sensors in the wheels.
  To elaborate, an indirect TPMS typically relies on wheel speed sensors that the anti-lock brake system uses. These sensors measure the rate of revolution each wheel is making and can be used by on-board computer systems to compare with each other and to other vehicle operation data such as speed.
  Based on the rate of revolution of each wheel, the computer can interpret the relative size of the tyres on your vehicle. When a wheel starts spinning faster than expected, the computer calculates that the tyre is underinflated and alert the driver accordingly.
  So, an indirect tyre pressure monitoring system doesn’t actually measure tyre pressure. It’s not electronically processing the same kind of measurement you might see with a tyre gauge. Instead, an indirect tyre pressure monitor simply measures how fast your tyres are rotating and sends signals to the computer that will actuate the indicator light when something in the rotation seems amiss.
  Examples: Since the Indirect TPMS is part of the ABS assembly, so an aftermarket setup is difficult to find. The car manufacturers integrate the sensors directly during production.

• Pros:
  Relatively inexpensive compared to a direct TPMS
  Requires less programming/maintenance over the years than a direct TPMS
  Less overall installation maintenance than its direct counterpart

• Cons:
  May become inaccurate if you purchase a bigger or smaller tyre
  May be unreliable when tyres are unevenly worn
  Must be reset after properly inflating every tyre
  Must be reset after routine tyre rotation

• dTPMS or Direct TPMS: Directly measuring, hardware-based systems. In each wheel, most often on the inside of the valve or the rim, there is a battery-driven pressure sensor which transfers pressure information to a central control unit.
  Further, sensors in a direct TPMS may even provide tyre temperature readings. The direct tyre pressure monitoring system sends all of this data to a centralised control module where it’s analysed, interpreted, and, if tyre pressure is lower than it should be, transmitted directly to your dashboard where the indicator light illuminates. A direct tyre pressure monitor usually sends all of this data wirelessly. Each sensor has a unique serial number. This is how the system not only distinguishes between itself and systems on other vehicles, but also among pressure readings for each individual tyre.
  Examples:
  For Direct TPMS, there are examples galore to choose from the market:
  JK Tyre Treel, Manatec Tyremate, SensAiry, Blaupunkt etc. And our forum is also abound with reviews for some of these.

• Pros:
  Deliver actual tyre pressure readings from inside the tyre
  Not prone to inaccuracies because of tyre rotations or tyre replacements
  Simple resynchronisation after tyre rotation or tyre replacements
  Batteries inside the sensors usually last for about a decade
  May be included in a vehicle’s spare tyre

• Cons:
  More expensive overall than an indirect TPMS
  Though simple, resynchronization may require costly tools
  Battery rarely serviceable; if the battery is drained, the whole sensor must be changed
  Proprietary systems make installation, service, and replacement confusing for consumers and auto shops
  Sensors are susceptible to damage during mounting/demounting

Summary:
A TPMS is a great thing to have in your car. Although the methods may be different, both direct & indirect systems serve the same purpose and activate the same indicator light.
Even though a TPMS can deliver accurate alerts when properly maintained, it’s not a replacement for manual air pressure checks, consider it just another item in your car maintenance checklist.

Now onto the poll, hoping that the above information has provided you adequate information to make an informed choice.

Request you to answer the poll Qs and share your views & experiences, as applicable.

Thanks.

Thread moved from the Assembly Line to the Tyre & Rims section. Thanks for sharing!

Have indirect TPMS and hate it. It only detects a difference in tyre pressure at speeds above 60-70 kmph. The last time I had a flat tyre at crawling speeds, it didn't even alert me. There is no substitute to proper TPMS, having the accurate PSI readings is also such a boon.

This happened at low city speeds. My TPMS thought "all is well", not even a warning:

I have a direct TPMS (extrenal). I found this to be extremely useful for my car. Sometime last year, RL tyre in my car had an issue with the valve leakage and the pressure loss was very slow. Without this TPMS, I would have had to keep checking the pressure every now and then to realize this leak.

I completed 8 long years with my Xcent and like most, already started contemplating on my next new drive. However, feelings are a thing that are difficult to bury and this thread knocked some more facts into my motor head.

https://www.team-bhp.com/forum/ownin...rade-swap.html

So, I said, if not a new machine, then upgrade it is. And that is how I ended up buying internal TPMS for my car with a new set of tyres and I must admit, its a must-have and not just another fancy add-on. I am so much at peace now without worrying about the air pressure in my tyres especially when you don't ride regularly and if you do - its long highway drives.

All the plus point are already listed above, but peace of mind tops for me.

Voted doesn't have and I manage.

Never experienced an indirect TPMS but reading through its clear that I will never trust it.
The proper TPMS is quite useful but only if it comes factory fitted although I am still in two minds about the sensor being linked to the battery life. But I don't consider it a need.

Till then air-fuel tandem refills and the Stanley tyre pressure gauge have been doing the job quite well.

TPMS is a safety feature like airbags and ABS. One can manage without them. But highly recommended to keep one as a safety precaution. There are plenty after market systems available at few thousands. Must have in a car.

Since JK Tyres have launched their "Smart Tyres", i.e , tyres with TPMS, and since the local JK Dealer is a friend, all my vehicles have JK Tyres TPMS.

Never really had a problem with the tyres, but, does help when I air down the Montero tyres for Offroad trails.

Both the cars I have direct TPMS, one being aftermarket internal TPMS and works perfectly fine with mobile app.
Couple of years back I never felt the need of TPMS. Now after being used to it and the benefit it brings, I cannot imagine driving without direct TPMS :)
For me TPMS along with mobile inflator is more important and serves better than a full size spare wheel.

I have Hyundai Venue 2020 model which came with the lowline type of TPMS. Frankly speaking, this type of TPMS ie the lowline type is as good as having nothing. It doesn't gives any tire pressure or temperature reading. It only illuminates the warning lamp on instrument cluster of car when any tire has pressure lower than 7-8 psi than the recommended one.
The biggest folly is that you never know which tire is the culprit. If any tire is punctured, and has seriously low pressure, you can make out visually, but if it's just a fresh hit, you need to check every single tire manually.
And to make matters worse, if I change the tire with the spare one, it will keep showing the warning lamp on console till I visit Hyundai service station and get the sensor deactivated or else till I get original tire repaired and fix it back at its place.

I have direct internal TPMS installed in all 5 tyres for both my vehicles. It's from Sensairy brand. The readings of both temperature and pressure are fairly accurate. It's easy to monitor and top up the tyres as needed. I have portable inflator which makes it quick fix. Few years earlier I had a puncture while traveling and didn't realize it until the vehicle started pulling to one side. Was almost on the verge of getting stranded on the highway with the stepney also low on pressure. Now I make it a point to keep puncture repair kit and the inflator in the boot whenever going on a road trip.

Don't have TPMS, but really want it.

Felt the rear left go really soft on a drive last week,
Stopped after 1km to check and lo and behold,



it doesn't end there,

the stepney was low on pressure too.

Called dad up and we took both wheels in the honda city to a puncture guy
TPMS could've saved me a good hour or two that day. Thank god I wasn't on an emergency.

I'm an early adopter of direct TPMS - in 2009, my Scorpio VLX had internal direct TPMS with constant tyre pressure and temperature display on the dashboard. The tyre sensor batteries lasted for over 9 years, and I've never had to replace them in all the years the car was with me. The only potential problem with an internal sensor is, if the tyre deflates completely and rolls, the sensor would break and need replacement. But that's what TPMS is for, to prevent the driver from running (and ruining) a completely flat tyre!

Since then, I've also used the cheap TPMS with external sensors on my other cars (had procured a few sets from Aliexpress when they gave it at throwaway prices), and haven't had any issues apart from needing to replace the batteries once (CR1620 button cells IIRC), because the reading started going haywire. I've not had an issue with sensor theft yet, but once lost a little rubber gasket from one of the sensors - that took me a while to find, and I now have a couple of spare gaskets. These cheap units are by and large reliable and durable, though I tend to remove them from the dashboard top during summers (the heat damages the LCD screen & solar panel).

I've managed to trigger a false positive warning on indirect TPMS in a Škoda Octavia when taking fast turns in the hills, due to wheelspin on one side, and that, coupled with the inability of indirect TPMS to read tyre temperature, is why I am not a big fan of the system.

Its a good idea., but it's not there on my current car, Baleno. With city driving and tubeless tires, it is usually manageable, What's the cost differential between a regular and tpms tyre set? And recommended tyre brand(s) with tpms. And are there apps to accompany or some physical hardware to show readings for aftermarket tpms kit?

I have an internal TPMS and trust me, it's one of the best features. The XUV3OO has monitoring system on all tyres (yes, even the spare). So, when the psi goes below 29 psi (recommended is 34), it throws up a warning on the MID. I find it very useful because we generally are not fully aware of the spare and the air in it. Also, I never use an outside gauge to check the psi in the tyres. I simply ask the guy at the petrol pump to fill air in all the tyres for 4 secs and I monitor the TPMS on the screen. It is dynamic and changes instantly. As soon as it reaches the recommended level, I ask the guy to stop. The TPMS also shows the temperature on each tyre. Usually the tyres heat up after a long drive, so that's a good indication of the overall health of the tyres. Bottom line - can't live without this feature!

My Tiago doesn't have it but surely it is very useful and i would be installing it in future. Better to have information before the tyre is completely flat...

Confused a little as to which one should i go for hardwired with a display in cabin or go for the sensors with information displayed in Mobile phone.

Guidance will be helpful

regards