The TireChek principle of operation allows for amazing performance! TireChek can be configured for INCREDIBLE sensitivity to loss of pressure in a tire. A specialized version of TireChek could monitor racecar tires for EXTREMELY small changes in tire pressure! A pressure loss of as little as 0.014 PSI could be recorded by the pit crew from telemetry from the car! They could then closely monitor that tire's pressure to see if it continued to lose air. This extremely early warning could represent the difference between life and death at 200 mph if a low tire is about to go away. More than that, at the speeds of racecars, fairly small changes in tire pressures can severely affect the handling of the vehicle, so this very precise information could assist a crew in improving competitiveness.
More importantly, that same tire is ## % more likely to fail and blow out while you or a family member is driving. Then there would certainly be the towing and repair charges. There would be the inconvenience. What about the potential of an accident? What about being stranded at night in an unfamiliar neighborhood?
Wouldn't it be GREAT if there was an inexpensive monitoring system for your car that would continuously be alert for any quick OR SLOW air pressure loss in any of the tires? THERE IS! We have invented TireChek!
TireChek is not yet available on the market. In the early Spring
of 2000, we contracted with a company in Florida to manufacture
the TireChek systems. There are not any technical problems, but that
company has had delays in getting production under way. Whenever they
start manufacturing the units, we will let you know on this page!
We first thought they would be in production by now, but we have now
removed our reference to a specific availabililty date. Sorry!
The initial selling price, including all necessary parts,
is expected to be $99.
For a handy person, less than an hour's work should install TireChek.
For less handy people, we expect that many auto repair shops will soon be carrying TireChek but they would likely charge a little more because of their cost of installation.
Installation of the TireChek System is fast and easy. As mentioned above, a person who is reasonably familiar with vehicles should be able to install everything in less than an hour. In an auto repair shop, a team of three technicians should be able to install the entire system in about five minutes on any normal car!
Once the installation is complete, each of the tire pressures are checked with a good gauge. The vehicle is then driven away! Within a minute or two, one or more of the TireChek warning indicators will light. Knowing that the tires are at the desired pressures, the INITIALIZE button is then pressed. That's it! (Pressing INITIALIZE teaches TireChek that each of the tires is at the pressure YOU desire.) The entire system is installed and calibrated that quickly! You will never have to press INITIALIZE again unless you replace a tire or if you add or intentionally remove air from a tire.
During installation, the wheels (usually) do not even have to be removed from the vehicle! The tires do NOT have to be dis-mounted and re-mounted, nor do they have to be re-balanced!
(Remember the Ideal Gas Law from Chemistry in High School? PV=nRT? For this situation, V, n, and R are relatively constant, so the pressure [P] is nearly proportional to the [absolute] temperature [T]. In winter, tires that are at 0°F [459 absolute] are at say, 30 PSI [45 psia]. After driving at high speed for a while, those tires are at 200°F [659 absolute], so the pressure has increased to [64 psia] 49 PSI! Isn't that interesting?) If you measured them then, and got a reading of 40 PSI, you might think that you should remove some air, when in reality, the tire was 9 PSI low already!
These continuous changes in pressure can really complicate the situation of a driver monitoring them. There are several VERY expensive tire pressure monitoring systems on the market that actually install pressure-sensors and transmitters inside each tire, to measure real pressures in each tire. The information on that pressure is then sent by radio signals to a receiver inside the vehicle. Unfortunately, a sophisticated computer is then necessary to correlate that measured pressure with the day's temperature and the tire's temperature, to be able to determine if the measured pressure is within the proper range. (For example, in the case mentioned just above, the system would need to understand that 37 PSI was actually an under-inflation condition!) Such high-tech systems are necessarily VERY expensive, because they include a wide variety of expensive individual components. And, regarding the future, think about who could possibly maintain or repair that exotic system if (when?) it fails, and how much THAT would cost! And, because of all the external variables that can affect tire pressures, such systems often cannot be set as precisely as they are capable of. In addition, since those competing systems generally install complex electronic devices INSIDE the tires, those devices are subject to the tremendous vibration of that environment, the occasional VERY high temperatures (which are detrimental to electronic devices), and their sensors and transmitters are powered by tiny batteries that are also inside the tires and will eventually fail. Wanna take a guess at what a local tire dealership will charge you to take the tire apart (to get to the sensor/transmitter) and then for their mechanics to stare at this exotic transmitter device, trying to figure out where the battery is? And how many days your vehicle would be out of commission while they try to find replacement parts (or, more likely, whole sensor/transmitters)?
TireChek does not require any exotic electronics to be inside the tire (or actually anything at all inside the tire), and our system is FAR less subject to all of those kinds of problems and failures. And even if something would ever fail, repair should be very simple and easy and inexpensive, and at no time would the vehicle need to be out of commission!
TireChek is able to sense VERY small changes in tire pressure. The theoretical design enables the possibility of detecting changes as small as 0.014 PSI! That's 1/70 PSI low! (Actually, theoretically, even less than that!)
In the real world, this extreme accuracy is impractical. When you drive around a corner, centrifugal force on the vehicle causes a weight transfer to the 'outer' wheels, which instantaneously fractionally increases the pressure in those tires. When a driver sits down, he/she adds a human body weight to the vehicle. This actually very slightly raises the pressures in ALL four tires, with the actual pressure rise in the two driver's side tires a little more than in the passenger side tires, and by different amounts! Of course, THIS effect depends on the weight of the driver! Other systems are not sensitive enough to have to be concerned about such minute changes, but TireChek is so sensitive that we found it necessary to consider such things! Because of many variable like this, we have initially chosen a detection threshold of about 3 PSI for normal cars (0.2 PSI for racing cars, because they have far fewer variables that can affect the readings) to minimize false alarms. TireChek systems with the optional yellow indicators sense about 1/3 that, or 1 PSI. These yellow indicator lights are likely to occasionally light due to the kinds of things mentioned above. The TireChek system is a continuous monitoring system, though, and such false indications soon clear themselves unless an actual loss of pressure has occurred.
No one else can accomplish this kind of sensitivity, even in VERY EXPENSIVE computerized systems. We monitor the tire pressures in a unique way (now in the Patenting process). We are then able to get our great sensitivity to air loss by continuously and instantaneously monitoring and then COMPARING the pressures of the two tires on the vehicle. They normally experience the same day/night temperature variations. They normally heat up similarly while you drive. This allows us to set our sensitivity to be WAY better than other systems! Maybe someday they will let us teach them this wonderful improvement!
If either of the two starts to lose any air, EVEN AT AN EXTREMELY SLOW RATE, our TireChek will alert you, well before it would be obvious visually or even on a tire pressure gauge. Many drivers check their tires visually. Modern stiff-walled radial tires can be much more than 5 PSI low and will still appear normal visually! Even when checked with a tire gauge, inaccuracies can occur, since some inexpensive tire gauges can be inaccurate by several PSI.
In case you're thinking this means the system will be so fussy that you have to be super precise about filling your tires, be assured! (That IS actually necessary in some of those expensive competing systems!) Once you have aired your tires to the proper pressures you desire, you just touch the INITIALIZE button on the TireChek panel if and when any red warning lights appear. The TireChek system would then understand that each of the tires are now at the pressures YOU wanted them to be at. Even if you intentionally fill them to different pressures! Even if you have un-matched tires on the axle! (That is not recommended, by the way!)
In the event of a very slow leak, TireChek would alert you as soon as any of the tires was low enough to match the threshold PSI difference that that version of TireChek was configured with! All of the advantages mentioned above that are related to maintaining tire pressure would be yours!
As a bonus benefit, in the event that a tire picked up a road hazard, and represented a true and immediate safety hazard, you would almost immediately know that there was a problem. You would then likely have plenty of time to slow down to a safer speed. There's even a good chance that you might have enough time (at that slower, safer speed) to get to a tire repair center well before the pressure got down to a dangerous level.
Finally, in the very remote possibility that a tire had a hidden defect, where it was subject to heating up unusually rapidly during driving, the TireChek Monitor would alert you to have your tires checked.
TireChek! Something you SHOULD have on your car, truck, RV and trailer!
This requires both pressure sensors and radio transmitters to be installed INSIDE each tire. It also therefore means that a battery must also be installed in there to power the transmitter.
It gets more complicated. The pressure of a tire is tremendously dependent on the tire temperature. That's why they always tell you to measure tire pressures COLD, before driving very far. The air in a tire that is pressurized to 32 PSIG when cold will obey the Ideal Gas Law and rise in pressure as the tire heats up. Since extended highway driving can get the tires up to over 200°F, those tires can 'naturally' get up around 50 PSIG pressure readings after several hours of highway driving. This means that a temperature sensor must also be installed inside the tire.
Each tire regularly sends radio signals to a computer inside the car, which passes along the digital data on pressure and temperature at that moment. The computer then has to calculate, based on the tire temperature, the proper pressure reading that SHOULD BE in the tire due to tire heating. Then it compares the ACTUAL pressure it has sensed with that intended pressure. If the tire is below that amount by a threshold amount, a warning is given to the driver.
Doesn't this seem awfully complex? And, you can probably see why some such systems have been sold for around $3,000. But, have you thought about the fact that electronics devices are a little 'delicate'? Inside a tire, there is enormous vibration and extreme heat. And, what about having to replace those batteries in a few years? The tires would have to be taken off the car and taken apart to replace them. And, your normal tire place might not have a technician that has ever even SEEN that particular system, much less know how to work on it or even change the battery!
And, during installation in the first place, the wheels have to be taken off the vehicle, the tires dis-mounted from the wheels, the sensor/transmitters installed (firmly!), the tires re-mounted, re-balanced, and replaced on the vehicle. This is essentially a big production!
Since almost no one will be trained to repair such a complex system (in those nasty vibrating, hot environments), how much do you think a repair person would later charge you to replace the batteries or to repair or replace a failed sensor? Since he knows that you cannot go anywhere else, he could charge virtually anything he wishes! And you don't even have a paddle!!
Consider if you were NOT given ANY measuring device or sensing equipment. How would you KNOW when a tire had low pressure? The answer is obviously that if the pressure was low enough, it would appear "flat".
What does that actually mean? The technical reason a tire looks flat is this. That tire supports a certain number of pounds of load, say 900, or around one-fourth of the total weight of a vehicle and passengers. If that tire contains air at 30 PSI, it would be necessary for there to be 900 / 30 or 30 square inches of area in contact with the road. If the tread is 5 inches wide, the tire's footprint would therefore normally be about 6 inches long. (30 square inches of footprint times 30 pounds PER square inch equals 900 pounds). (These numbers are actually approximate, because there are other factors involved. For example, the stiffness of the sidewalls of tires would actually support a little weight even if the tire had no air. But the general point we are making is quite true, and obvious.)
If that tire lost air such that its internal pressure was just 20 PSI, the load is still 900 pounds. This means that there must now be 900 / 20 or 45 square inches of area in contact with the road. The tread width is still 5 inches, so the footprint MUST now be about 9 inches long. (45 square inches of footprint times 20 pounds PER square inch equals 900 pounds).
A symptom of both of these situations, the desired and the "flat" is that the bottom of the otherwise round tire appears to be flattened. In the desired case, the flattened area is 6 inches long, and in the "flat" case, the flattened area is 9 inches long. So, when we say that we see that a tire is "flat", we are actually saying that the flattened area is larger than we think it should be.
The argument just presented is true. The numbers are not precisely accurate, because the sidewalls of a tire have some structural rigidity, which contributes to supporting the wheel's load. In low profile tires with steel radial belts and stiff sidewalls, this contribution can be substantial, but all practical pneumatic tires support most of the load by the pressurized air contained within it. This comment just means that the numbers presented above are approximate for real tires.
This explains WHY it happens. Now HOW does it occur? Simple geometry shows that the only was the footprint could get longer is by having the effective radius of the tire become less. Draw two identical diameter circles on a sheet of paper, and draw a straight line to "slice off" a thin sliver of the circle on one and a different line to slice off a wider sliver on the other. The flattened area of the circles represents the footprints. It is easy to see that the distance between the center of the circle and the line is different for the two. The flattened area is closer to the center of the circle for the drawing with the larger "footprint".
That's why a vehicle appears to have a corner of the vehicle physically low when the tire is entirely flat or nearly so. With the "effective" radius of the tire being less, the axle shaft centerline of that wheel is actually lower, nearer the road. You can easily see that the effective radius of the tire is geometrically directly related to the size of the footprint, which is directly related to the pressure inside the tire.
So, if a system VERY precisely monitored the height of each wheel's axle shaft centerline above the road surface, it would also monitor a tire's pressure!
Please notice several important facts. NO device needs to be placed INSIDE any tire. No transmitter in there would ever need battery replacement. System installation does NOT involve dismantling the tires and wheels, and the TireChek system can generally be installed without even removing the wheels from the vehicle! The wheels do not have to be re-balanced.
Essentially, we have found a totally different way to monitor each of the tire pressures, which does not actually require pressure sensors, but which turns out to be even more accurate and sensitive!
It is not possible for anyone to recognize a tire being low by 1/8 inch. In general, with modern tires, a tire must be 7 to 10 PSI low before the driver notices it either by sight or by odd handling of the vehicle.
It might not even seem very possible to continuously monitor each of the wheel's axle heights, without incredibly involved distance sensing radar systems! And, even with such a system, variations of road surface heights (like potholes or grading) would keep precise accuracy very difficult to obtain.
TireChek is designed to continuously monitor the effective tire radius. We invented a way to rather simply and inexpensively monitor the axle heights of the various wheels to an accuracy that can be better than 0.001" in height difference! This amazing precision corresponds to a pressure loss sensitivity of around 0.03 PSI in a tire! In other words, with TireChek, it is not necessary to wait until a tire loses 7 or 10 PSI where it is either visible or the vehicle handling is affected. The TireChek system could give an alert if any tire was even 0.03 PSI low! And, it would indicate just which tire it was!
Now, in real life, there is little need for such incredible sensitivity. (In racecars, there IS, and the extreme sensitivity of TireChek would be used, and even enhanced further!) Such extreme sensitivity tends to result in occasional false warnings. For this reason, the normal TireChek system is set up to give a RED ALERT if any tire is 3 PSI low. The second version does the same, but also gives a YELLOW ALERT of any tire is 1 PSI low.
Since TireChek is a continuous monitoring system, if it would happen that unusual circumstances caused a warning, within one minute, new pressure analyses would either cancel the warning or confirm it. This represents a self-diagnostic for the TireChek system. A warning that persisted would always indicate a real tire pressure loss!
Just HOW TireChek is able to monitor all of the axle heights to within 0.001", well that's central to how TireChek works! TireChek not only does this, but it does it in a system that is FAR less expensive than any competing monitoring system. TireChek does not NEED exotic pressure and temperature sensors and radio transmitters inside the tires. TireChek even has a far simpler computer as part of the system! Even better, future repairs should be very rare, and inexpensive if ever necessary!
It may have occurred to you that tandem tires might represent a problem for TireChek. That actually turns out not to be the case. The axle height of a dual or tandem tire is actually determined by the AVERAGE of the tire pressures in the two tires involved. It's another application of that "footprint" logic described earlier. If EITHER tire of a tandem would lose air, the axle would still lower, but only by about half of the distance expected with a single tire. Since TireChek has such extreme sensitivity, all that is necessary is to double the sensitivity setting for a tandem tire, to achieve a pressure loss sensitivity similar to that of TireChek configured for a single tire.