Accuracy Of Tire Pressure Monitors

[bullitt]

Does anyone have a feel for how accurate the tire pressure monitors are? When we picked the car up a month ago, the tire pressures were uneven (31-34 psi). We asked the dealer to check the pressures and they adjusted them but the monitors still showed one or two psi difference.

I bought a decent tire dial-type pressure gauge recently (a "professional" model from Checker, so I can make no claims of accuracy for it) and carefully adjusted (and double checked with an older tire gauge) all tires to read 33 psi. The internal monitors showed two tires at 31 psi and two at 32 psi. The tires were "cold" (not driven since the day before).

I realize the dial gauge could still be off a psi or two and the actual pressures may be on the border line between two readings ("31.5"). Is there spec on thne asccuracy of the monitors? Is it possible to buy an truly accurate tire gauge? Other than what NASCAR teams use, of course, since they probably are gold plated and more than a little pricey.

Silver Bullitt

[JAM123]

Is there spec on thne asccuracy of the monitors? Is it possible to buy an truly accurate tire gauge?

Silver Bullitt

I have not seen any specs. I do have a person at Discount Tires who has been looking at the aftermarket, but has run into some problems due to proprietary issues.

Please not that based on my experience, the accuracy of these monitors are highly debateable. I have tried every combination of guage and air temperature to get all of tires to read the same and they do when cold. When hot; the psi spread between the monitors at times can be as much as 6 psi. So I treat them as "for monitor purpose only" and keep an eye out for unusual swings in the readings... time to check the tires for any leaks.

[SW03ES]

Your hand guage will be much more accurate. The system is really designed to notify you of significantly low pressures.

[mehullica]

The system in the LS460 is extremely accurate. The display on the combo meter is rounded to the nearest whole number. The actual reading as viewed with the Lexus techstream PC is accurate to to +/- .1 psi, and +/- 2 degrees F for temperature.

[JAM123]

The system in the LS460 is extremely accurate. The display on the combo meter is rounded to the nearest whole number. The actual reading as viewed with the Lexus techstream PC is accurate to to +/- .1 psi, and +/- 2 degrees F for temperature.

Technically it is but in reality I beg to differ. Could the error be induced by the RF between the monitor unit and the LT PC.

[gordonw]

I don't get it. It seems like a waste of time to try and get all the presures exactly the same. What would be the point, as long as they close enough. Even if you could get them the same, what happens once you start driving the car. I'm willing to bet that over time the tires will become a little underinflated as they always have and it won't be even either.

[bullitt]

I don't get it. It seems like a waste of time to try and get all the presures exactly the same.

Hey, I'm an engineer. Engineers do stuff like this.

However, you are correct in assuming a psi here or there doesn't matter much (unless you are trying to avoid the dreaded push at 200 mph at Daytona in turn 3).

Silver Bullitt

[bullitt]

I did a little Googling and found

http://townhall-talk.edmunds.com/direct/view/.ef017dc/0

Someone did lab comparisons of various tire gauges. Summary:

Stick or pen type gauges (with the white shaft that pops up) tend to read 1-2 psi low

Dial type gauges tend to read 1-2 psi high

Most digital gauges read pretty close (1 psi)

Stick types should be lubed with WD-40 every so often.

You may see a 5-8 psi difference between various gauges.

It is possible for a gauge of any type to be right on (your results may vary).

The "Accutire" brand digital gauge that sells for $10-30 at Sears and other places has great accuracy (+/- 0.5 psi), highly recommended although some foks felt it didn't seat well on some tire stems.

Silver Bullitt

[JAM123]

I don't get it. It seems like a waste of time to try and get all the presures exactly the same.

Hey, I'm an engineer. Engineers do stuff like this.

Silver Bullitt

Me too. LOL....... In Pursuit of Excellence.