Does the TPMS for your car include a calibration certificate?

In my line of work (automated dispensing systems) I deal with various types of pressure sensors. IMO repeatability is far more important than calibration.

I must have 5 or 6 separate tire gauges at home. No two of them read exactly the same for a given tire. If it reads 34 psi when the pressure is actually 36, do I care? No, just as long as it always reads 34 psi.

I am not trying to build rocket ships here, I just want to be reasonably sure that I have about the right amount of air in my tires.

Unless you are sending your gauges out for calibration on a yearly basis or buying new calibrated gauges yearly you have no idea how close your gauges actually read.

 

My car does not have TPMS so it matters not. It also has 4 wheels so with differing tire pressure it is inherently more stable and safer at speed than a two wheeled vehicle. I agree with you that repeatability is important (over a quantifiable +/-range,) but without an accurate standard to compare against it is meaningless. A quality manufacture of any industrial gauge will always spec percentage accuracies over a particular scale, rather than repeatability accuracy. This way if the device has not been calibrated you still know that it is, for example, 2% accurate mid scale, 3% accurate over the bottom 20 percent of the scale, and 1.75% accurate at the top 20 percent of the scale.
If the purchaser of the TPMS device has no way of knowing the scale's accuracy then the repeatability factor is useless to the user. It would only be beneficial if the user, at his own expense compares the device over its range against a calibrated source. This is something that should be done at the factory for the high dollar amounts being charged for these TPMS devices.
I get a chuckle when I see offshore digital tire pressure gauges being touted as 0.5 psi accurate. Accurate over what? That bit of marketing hype tells the buyer nothing. A $20 gauge I can understand not being calibrated, but laying out better than $150 or more I expect some a certain diligence on the manufacturers part. Speedo's have to be accurate to a Federal standard, why not tire gauges?

 

Who is "going to layout more than $150"? These things are not near that expensive....

TPMS was mandated in all US cars phasing in beginning 2005. That means that by now most cars on the road have them. You personally may not, but most people do.

You still did not answer the question. Are your air gauges calibrated and if so are they within their calibration window? If they are not why would you require these dongles to be calibrated?

 

I have the tpms on my triumph. I can check the numbers on my dash and if it drops an alert shows on the dash. I manually check about once a week and the tpms is pretty reliable.

 

When TPMS 1st showed up on my cars I was very skeptical about the accuracy. I checked them with my trusted Accugages and was pleasantly surprised to find out that in a Camaro and 2 Mustangs they were almost exact.
I assume the aftermarket ones would be the same.

 

Thanks for the review

 

I have purchased this system as well for my 2013 EGC. I bought the "T" metal valve stems. I am assuming those may be problematic with the wheel design.


Oh, by the way. From what I understand, you do not have to use the locking nuts that require use of the wrench. You can simply screw them on just as you do your valve stem cap.


I do agree that checking tire pressures on my Electra Glide is a huge PITA, and that was my motivation for buying this. In hindsight, a more economical solution would probably have been to buy the valve stem caps that have the clear cap that shows green if the tire is at the correct pressure.


I love having the instant information on my BMW, and wanted the same for the Harley. If you don't want it, don't buy it. We all aren't alike...it is nice to have choices.


John

 

Yes, My personal gauge is a Moroso 89562 0-60 psi tire gauge, I calibrate it myself at work to the ANSI B40.1A standard (1% accuracy.) ANSI 40.1B standard is 2% and is the accepted standard in automotive tire work. After 7 years its dial accuracy has never faulted past 0.15%, thus it has never required any adjustment.
The auto store tire gauges that I've tested were almost never accurate, most being out 1-6 psi plus/minus. For me that's not good enough. If my StreetGlide front tire drops to 31psi the handling at 70 mph gets very squirrelly, I don't want some store bought tire gauge displaying 36psi if it's accuracy is unknown, even if it's repeatable to 0.5 psi.

 

Might one inquire as to how you read a 0 - 60 psi gauge to 0.15%. Per the Naval Nuclear Power program and NQA-1 you cannot read an analog gauge to less than 1/2 it's smallest marked increment. This would equal .25 psi on your (admittedly very good) gauge. Your claim on accuracy never being worse than 0.15% (I assume of full range since you did not specify) means that you are claiming to read the gauge to .135 psi or about a quarter of the smallest increment.

Skipping all that, and admitting that you, personally do appear to have a calibrated tire gauge (with an up to date calibration), how many of the rest of us do you honestly think have one. Seriously, how many people who are not in the business (Automotive or tire engineer, racing...etc) do you think actually have a $150 calibrated tire gauge (with up to date calibration)? If they don't have that then why would they require calibrated TPMS?

 

Learned a little about how much temperature affects tire pressure. Last winter I had the TPMS light come on in my car. It was 20* below 0 and when I checked the pressure it was indeed low. I suspected it may have something to do with the extreme cold. I did a little research and found out that for every 10* change in temperature you gain or lose 1 PSI. So if I checked tire pressure in August at 80* and it was 35 psi, the pressure at 20* below will be 25 PSI hence tripping the TPMS light to come on.