TPMS reads 5 PSI high on all corners

Ive got about 1000 miles on my new Tacoma. I finally had time to check a few things. The TPMS was reading 30 psi all around. Checked them all with my tire gauge (very high quality oil filled analog race gauge) and it was showing 25 psi. Hmm. Filled them up and of course the TPMS now reads 35 all around. I looked at the Owners Manual and did the initialization procedure, but it didnt change the readings.

Is there a way to calibrate the sensors? Its not my gauge. Ive checked it against a few other pressure gauges.

 

I'd be curious if they can be calibrated too, as I have the same issue. Mine check @ 32 PSI with a pressure gage, but the display is showing 37 PSI.

 

Mine is off too but only on one tire. If you search forum thread titles for TPMS you'll see my post. I really am not a fan of TPMS at all. Just another idiot light to come on that I never needed in any other vehicle I've owned previously. They cause more trouble than they're worth.

 

Mine is the opposite of you guys. Mine reads 35psi but on 2 different tire gauges reads 40 psi. I thought it was just the gauge so that is why I tried another one and sure enough 40 psi.

 

All tire pressure monitor systems are just a rough estimate of pressure. Every manufacturer has this issue. They are one little sensor talking to a receiver talking to another computer and then dumb down to your instrument cluster. I believe 10% plus or minus is the industry standard but I'm not a hundred percent on that. Nothing beats a high-quality analog gauge for checking your pressure!

 

Are there any that you would recommend or can provide a link to

 

I use Intercomp guages and they are about as accurate as you can get. I have a couple of them, one for the MX bike which 1psi makes a huge difference and one for the vehicles. They also have release valves to get the exact pressure you want.
http://www.intercompracing.com/gauges/air-pressure-gauges.html

 

Any snap-on, Mac, or Cornwell. Even Craftsman is going to get you close enough. You've got to buy the hundred-dollar one and not the $10 one. I can tell you though just out of curiosity one day I borrowed every pressure gauge in the shop I work in. I tested them all on the same Tire. They all veried within 5 PSI. Some of these gauges cost $250 and up. Even the multi-thousand-dollar Air Products nitrogen machine varied a few PSI. The point is your tires heat up and cool down and fluctuate in pressure you're just going to try to get it to that recommended setting with what you have.

 

The tmps on my truck is off 2psi against my trusty old manual (and cheap $5) tire gauge, and it it’s accurate to within 1-2+-psi.
My 4” instrument display shows a 2psi difference between any given tire when cold and closes that gap to 0-1 psi once the tires are fully warm.
Johnson Controls makes millions of tmps for various auto makers, and is claimed or aimed at being to within +- 1psi accuracy.
IDK who makes Toyota’s tpms but I can image it would be within -+ 1psi from Johnson Controls system.
I would take it back to the dealer and have them check and address the concern because whether you want it or not, you have paid for it.
I know I would, even though I don’t rely on them as I’d rather check my own because quite honestly to me they are more a PITA then of any help to me and are an expense liability to maintain.
But that’s just me
Best of luck…Cheers!

 

I have an entire collection of gauges - from oil filled analog to digital....

No gauge will maintain its accuracy unless it's calibrated regularly - just like a torque wrench.

IMO, the best brand I have found - regardless of price is the humble Accu-Gauge by GH Meiser.

They will calibrate their gauges for life - free, simply pay a $3 fee for return postage.

I send them in several every Winter and that $3 charge covers return postage for ALL of them.

 

The TPMS is reading absolute pressure. The tire gauge reads differential pressure. They will not be the same. With a tire gauge, higher pressures will be read at higher altitudes, TPMS sensors will remain the same. Typically, TPMS sensors are very accurate.

 

No. TPMS is reading gauge pressure just like the tire pressure gauge. If TPMS was reading absolute pressure it would be lots higher.

Explaination for you:

PSIA = Absolute pressure is zero-referenced against a perfect vacuum, so it is equal to gauge pressure plus atmospheric pressure.

PSIG = Gauge pressure is zero-referenced against ambient air pressure, so it is equal to absolute pressure minus atmospheric pressure.

Differential pressure is the difference between two areas such as across a filter medium.

 

The TPMS sensors are inside the pressure chamber and have no access to atmosphere, thus they read absolute. Your tire gauge is working in atmospheric pressure. One side of your tire gauge works on tire pressure and the other is working at atmosphere. That is the only way these two gauges can work. The TPMS sensors don't add atmospheric to its reading, it reads inside the tire psi. Not here to argue. I've researched this during track testing and driving schools in my corvette years with discussions with people who actually know what they are talking about. This is not about a text book definition of absolute and differential pressures, this is the way the gauges work.

 

This might explain why my quality gauge consistently reads 3-4 psi higher than my tpms at 6500 ft.

 

Absolute pressure or not, if its not accurate its worthless. I have other TPMS equipped cars. One is within 2 PSI. One is dead on accurate with my gauge.

Also, not that it matters, but wouldnt absolute pressure be reading 14.5 psi higher than normal?

 

Tire was flat on the rim. TPMS still said 15PSI

 

Will checking the pressure with no weight on the tire be the same as when it is on the ground?

 

Dont think so

 

I know this is an old post but I compared my JACO 0-60 psi elite tire pressure gauge against the truck’s TPMS center dash reading for the first time today. The JACO gauge read 30psi cold (after I let some air out) and the truck display changed to 31 psi on all four tires after it automatically reset itself once I turned the ignition key back on. It took less than a minute for the TPMS display to go from four dashes (-) to four 31 psi readings after I let the air out (the tire pressures were too high because the outside temperatures have come up considerably). The truck’s display had been showing 38-39 psi during a road trip this morning. So a 1 psi difference.