I think you have it wrong.

If you investigate TPMS systems used on heavy transport trucks (semi-trailers), most of them use a system that is connected to the inflation valve and measures pressure at the valve, by keeping the Schrader valve depressed. There is nothing wrong with that design - but the safety and reliability of it is, of course, very much dependent on good quality components and meticulous quality control during the manufacturing process.

I use the Garmin TPMS on my motorcycle, primarily because my GPS supports display and monitoring of tire pressure via Garmin supplied pressure sensor caps that fit over top of the Schrader valves. I have complete confidence in this system - I have used it for 5 years and 60,000 miles without any problem, and it did save my bacon once when I encountered a puncture from a large nail on the highway.

Like anything else, you need to be a critical consumer when purchasing equipment, particularly safety equipment. I don't purchase anything from unknown Chinese (mainland Chinese) manufacturers. Garmin makes their TPMS sensors in Taiwan, which is a totally different environment and culture from mainland China, and I have trust in Garmin as a manufacturer.

In reply to the original poster, who asked about TPMS in general, my recommendation is to purchase a system from a manufacturer that has a reputation for quality and dependability. Personally, I like the concept of TPMS integrated with the GPS because it minimizes the number of different systems on the motorcycle, and enables the manufacturer to easily update the software that operates the TPMS. The only downside that I have encountered so far is that the little batteries that go inside the sensor have a maximum life of one year, and it can be difficult to buy them when you are on the road because they are an uncommon size. This means you need to carry a couple of fresh spares with you.

Michael

I can only speak for the manufacturer I work for but this is not the case with all systems.

An external retrofit solution puts a pipe on the valve that opens it. This volume is open to a gallery where the pressure-voltage transducer is and then continues to another schrader valve. The unit is mounted on the wheel nuts so puts minimal stress on the tyre valve. In the event of failure the original valve can close.

An external solution mounting a complete P-V wireless unit on a valve tube is adding stresses to a component not designed to ta take it. Some valve stems are in metal which helps but many are not. If the original stem fails there will be an immediate and rapid loss of air. An external unit that has to be removed to put air in is permanently holding the valve open, so air is held by something potentially tested to a manufacturers internal standard not a tyre valve international one.

Internal systems either valve or strap mounted are before the valve and do not stress the stem. These will be the standard when legislation comes in. Temperature is a more useful measure in catching a blowout than pressure and you measure this off the rim not the valve air.

Personally I'm not going to screw Chinese tat onto my valve stems when two tyres can be checked in seconds with a hand held gauge. I am motivated to do this. A truck driver with 20 to do is less motivated and car drivers are incapable, hence legislation here/coming on 3+ wheeled vehicles.

Andy

I bow to greater knowledge of the subject - I'm no expert (or even much of an interested bystander) but there's a huge consequential difference between a tpms cap failure on a 32 wheeler and on a two wheeler. Especially as a trucking co is likely to be using caps with some sort of track record (to minimise failure inconvenience if nothing else) whereas the bike aftermarket is likely to be a bit of a race to the bottom minefield - especially if all you have to guide you is marketing or word of mouth. Most of the ones I've looked at since this subject came up have been heavy on marketing 'sizzle' (bluetooth this, handlebar display that, app on your phone the other) and light on independant safety assessment of the cap itself. Maybe they are a genuine advance in road safety but they - all of them - are going to have to be at least as safe and reliable as the simple time served mechanism they're bypassing to justify their place. So far I don't see any of that.

In practice what's going to happen - if your tyre and valve are functioning as they should then very little happens - no air leaks out between checks. Add a tpms and it'll tell you - nothing, and if nothing changes it'll get ignored. If it indicates something amiss you'll check a few times and it turns out to be a sensor fault (my car experience of them) through the battery going flat or it's cheap electronics or water's got in or whatever it'll get ignored ('the damn thing's playing up again'). A gadget version of the boy who cried wolf. I might come across as some kind of mechanical luddite with this but not so - I'm usually closer to an early adopter than the opposite, but aftermarket tpms's don't form a complete risk / cost / benefit circle for me at the moment. They seem like a half developed technology.

If you read in BMW or KTM forums about issues on standard TPMS it sounds sometimes similar like a half developed technology.
Riders critisize periodic connection failures to the ECU. Some complain about variable unrealistic pressure data shown in high and low environmental temperatures.
Often these issues get more frequent when the TPMS sensor had to be replaced after 40-60.000 km. Problem with the sensor is that it is nearly impossible to replace the soldered in battery. You have to invest another 70-100€ for each sensor + installation costs.

BMW and KTM plug in Schrader Motorcycle TPMS.
https://www.schradertpms.com/en-gb/o...otorcycle-tpms

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Problems with not reading are down to the signal strength limits set by the EU. They are the same as alarm remote controls but don't take into account data has to be in complete chains not just on/off and that radio waves dislike metal cages.

Taking temperature into account is why you want an internal sensor and properly developed software, not some students project with an industrial P-V and the Bluetooth on his phone.

Sensor batteries get run down by endlessly trying to connect to a system that's just out of range, just like your phone trying to connect to duff wi-fi. Ultimately, assuming they cannot have a more powerful signal they'll mount receivers inside the mudguard to pick up sensors built into the tyre.

Andy

Pressure changes with altitude and temperature changes - which is not a fault with the TPMS. Riding will increase tyre temp. Higher speeds, tougher terrain, thicker innertubes, higher outside temp, will all make the tyres run hot - and pressure increase. The constant changes of pressure is not a fault with the TPMS (presupposing it is a reliable device).

My main reason for retrofitting a TPMS would not be to have a correct ambient reading, or have a temp sensor try to calculate it. My main reason would be to have an early warning system for loosing pressure - mostly while in the go. I would still probably be checking the pressure with a gauge sllmost as regularly as I do today, and less frequent as my confidence in the system grew.

The valve cap version would take seconds to retrofit, but are there any good ones that are compatible with innertubes? Do they pose a safety issue in themselves? I have no clue. When it comes to the valve type, I've read somewhere that the simpler varieties with a small handlebar display (of a recognized brand) is preferable to more advanced variety with larger displays, temp sensors, etc - claiming longer battery life, better reliability, etc. Wether that is good advice - I don't know - this tech is new to me.

As I change tyres frequently, I'm not too worried about the inconveniences of having to replace a battery inside the tyre - but the valve cap solution is such a smooth install... but only if it doesn't lead to a rapid loss of air 7n itself. Now, I hardly ever go above 140 km/h on an adventure bike. So, is the potential stress 8n the valve stem really an issue - or just anoter SoMe echo chamber "fact"? Again - I have no clue. I would however assume that if there was a real and significant risk of a technology such as this and which has been arround for s few years - that legislation would be out in place to sell or market them for such risky applications. Or am I just being naive?
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Cholo - I apologize for the insulting connotation of my response to your comment. It's just that your response could come across as something that advocates KTT - which to me falls in the same category as riding without gear, eye protection, open faced helmet, hiking boots, etc - all topics I am bit overly sensitive about. Sure, it is a personal choice - but one that comes at a risk.

I still don't for one second believe that one can eyeball pressure (except when close to flat), or even read it with any degree of accuracy by kicking, stepping or squeezing the tyre. Sure you can when you are dealing with a tyre that is flat or close to flat, but can you recognize 1/4 bar change? I sure can't - and I am no beginner. Even if I had hydraulic strength in my fingers, I don't think I could - and it is not for lack of trying. On a side stand, center stand, balancee, loaded or unloaded - I can't.

With the potential dangers involved in not being on top of one's wheel condition at all time - taking frequent and methodical measurements with a calibrated quality instrument is the only sound practice in my opinion. I still step on my tyres when I can't be bothered to take out the gauge - between the frequent gaugings.

As for making fun of riders that have crash bars, etc - I can think of many reasons where having many of the items you mention is more adviceable than not having then. That much said, I agree that for some applications, some people go a bit too far for their own good. This TPMS might very well be such a case for me - that is why I want to discuss it. For most of us, funds is a limited resource. For many of us, every item added comes at the expense of exponential amount of clutter in our life, more weight, more space consuned, more worries, and can over sll require more attention and concern than what it was intended to leviate, etc. Having one turn by turn GPS and a second with a route - I see it has its place. A GPS to replace your phone which doesn't stand up to heat - I get it. Still, one ought to be critical about these things - so at some level I agree with you... but definitely not on tyre pressure.

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While riding, I think it only works with tubeless. Think about Formular one or Rallye technic. They all use tubeless to receive exact data of the pressure and temperture sensor. Either you messure inside the tyre or you messure on the valve of a tube.

The advantage of tubeless is that you get exact temperature and pressure data out of the inner volume of tyre. Means if the data reading device is programmed correctly and detects failing pressure and rising temperature togehter than you should get immediatly a warning signal.

The problem with this valve cap is that it only shows pressure. Temperature detecting isn`t given. Due to weight of the caps and the law of rotating mass it is maybe necessary to counterbalanced the wheels. Also the valve stem or the part where it connects into the tube can be damaged too through this.

The display must be easily readable. It is equal if it is an external display on the bar or if it is done by your smartphone.
The critical thing is: How does the programming behind both devices interpret the data send by sensors? Equal if you use an external display or a garmin or a smartphone as a control device, a nice warning sign and a sound signal must be given to touch your attention.

From 2026 on all new motorcycles faster than 50km/h must be equipped with TPMS in the EU. Afaik you can still buy motorcycles with a valved bases TPMS since 2012.

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I think this review is quite informative. Here are a couple of bits of info I found interesting:

• $130
• Regular watch type batteries
• Valve caps weight less than 0,3 ounces and don't require rebalancing of the wheel
• Failure of non-metal valve stems is rare, though most innertubes comes with metal ones
• Compatible with innertubes
• Designed specifically for the adv motorcycle market

I wish the display was battery powered.

The reason I want a separate display and not have the kind where I have to rely on my phone:

• I don't always ride with my phone watched to the bike
• I couldn't be bothered to launch and check an app all the time. Even if alarms were running in the background, pairing still ought to be checked
• My phone is only attached to the bike when I am to use it for something particular, like navigation

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These sensors have a gravitation switch which is activating the electrical flow when the wheel starts spinning with 15-20km/h.

The sensor itself has no paired or bilateral confirmed wireless connection to the 433mhz receiver. It is just sending the data in fixed chronological intervals. All modern sensors send data of id, pressure and temperature but not every receiver shows temperature.

The 433mhz receiver is often hardware connected to the ecu and it only reads this data. There is no principle of trying to connect existing and necessary. If the signal cannot be received, you don`t see data. Therefor no complex software is needed because sensors talk in general trough simple commands.

This principle is also used by the TPM Systems with the caps(e.g.FOBO). The only thing which has to be fixed up in front for reading data is to tell the ecu or a seperate receiver(external display or smartphone) or a garmin trough an identification process which sensors is where.

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