[Noh Wan]

Has anyone taken an opportunity to compare the TPMS reported tire temp to the actual tire temp? I've read several threads stating the pressure readings deviate around 5-10% (usually low) and I'm curious if the report temp shares a similar deviation. I'm also curious if anyone knows what the TPMS reporting interval is?

[DanG]

My TPMS readings are 1-2 psi low as compares to my digital gage. From what I understand this is normal.

[medphysdave]

My TPMS sensors are 1-2 psi lower and 15 to 30 degrees F lower in temp when compared to my track connect sensors. Keep in mind the TC sensors are in a different location than TPMS.

[Noh Wan]

Thanks for the responses. I did some tests today and the IR thermometer confirms that surface tread temp is about 15 degrees F hotter than TPMS reported values. That 15 degree temp differential is pretty consistent at all four corners. I'll do a few more tests but it seems that the data is enough to get a generally accurate picture of what the tires are telling you.

Curiously, My RF tire is consistently about 5-7 degrees warmer than the LF and RR tires. The LR tire is a couple of degrees warmer than the other two as well. TPMS reports as much and the IR thermometer confirmed it. This is generally on flat interstate. Can anyone else chime in with some average tire temperatures? I'm specifically curious about the difference between different corners of the car and which corners are usually warmer or cooler.

Thanks again!

[medphysdave]

Around town today.

I adjust my tire pressure for cold weather. Now that it's warming up I'll pull 2psi from each tire to target 38psi for normal diving.

I found the TPMS to not be linear I it's report of temp. Its not uncommon to see 20 to 25psi difference. 30 is that max I've seen. This was in colder weather. The response might be better when ambient isn't 35F

[jdubm2c]

Originally Posted by Noh Wan

Thanks for the responses. I did some tests today and the IR thermometer confirms that surface tread temp is about 15 degrees F hotter than TPMS reported values. That 15 degree temp differential is pretty consistent at all four corners. I'll do a few more tests but it seems that the data is enough to get a generally accurate picture of what the tires are telling you.

Curiously, My RF tire is consistently about 5-7 degrees warmer than the LF and RR tires. The LR tire is a couple of degrees warmer than the other two as well. TPMS reports as much and the IR thermometer confirmed it. This is generally on flat interstate. Can anyone else chime in with some average tire temperatures? I'm specifically curious about the difference between different corners of the car and which corners are usually warmer or cooler.

Thanks again!

My driver's side front is always the warmest of the three by about 5 deg, and I believe that is due to a radiator being in/near that wheel well. The other three are pretty much the same unless on track or a spirited drive, and then it depends what you are doing and if you have traction control on, which could be braking on certain wheels without our knowledge.

[.Tranceparent.]

Guys, understand the factory recommended tire pressure is 35psi. Does this mean 35psi when at operating temps (say 80 degree tire temp) or cold? Trying to gauge the right pressure when I'm inflating tires before heading out for a drive.

[DanG]

Originally Posted by .Tranceparent.

Guys, understand the factory recommended tire pressure is 35psi. Does this mean 35psi when at operating temps (say 80 degree tire temp) or cold? Trying to gauge the right pressure when I'm inflating tires before heading out for a drive.

Originally Posted by .Tranceparent.

Guys, understand the factory recommended tire pressure is 35psi. Does this mean 35psi when at operating temps (say 80 degree tire temp) or cold? Trying to gauge the right pressure when I'm inflating tires before heading out for a drive.

Recommend pressure of 35 psi is the cold pressure.

[.Tranceparent.]

Got it. Thank you!!

[doughboy]

Relax, TPMS idrive display is just a fun gauge not some scientific instrument!

It measures tyre air temperature not tyre carcass temperature. The carcass temp will always be higher because its the heat from the carcass that in turn heats the air inside the tyre.

Puncture detection works on relative changes so the absolute pressure accuracy is not important for that purpose...

[///MPhatic]

Mine read low, about 2-3 psi each.

[Noh Wan]

Originally Posted by jdubm2c

My driver's side front is always the warmest of the three by about 5 deg, and I believe that is due to a radiator being in/near that wheel well.

Awesome! I hadn't thought about the radiator up there. Since three cars confirmed the behavior I can assume it's not a fluke. Since my Pass rear usually reads warm too I was wondering if the Pre-load is off in one of the corners.

Originally Posted by doughboy

Relax, TPMS idrive display is just a fun gauge not some scientific instrument!

Fair enough, but even a cheapie little Casio calculator has its scientific uses. If I can get more info than I can start to figure out exactly where the iDrive display fits on the Fun/Science spectrum (not that they're mutually exclusive). Temperature is super useful as a way to make inferences about suspension/alignment/chassis/tire dynamics, not to mention driving behavior. Is the TPMS as good as a Fluke pyrometer? No. Is it a snapshot of what the tire is doing mid-lap? It might be. I need more data. I could buy Cup2 Connects like medphysdave (Thanks by the way! Super useful data.) but this is WAY cheaper!

...and it potentially adds knowledge to the community... even if that knowledge is that the tire temp readout is garbage.

So what are your tire temps? Measured vs reported.

Thanks again everyone!

[doughboy]

Originally Posted by Noh Wan

Awesome! I hadn't thought about the radiator up there. Since three cars confirmed the behavior I can assume it's not a fluke. Since my Pass rear usually reads warm too I was wondering if the Pre-load is off in one of the corners.



Fair enough, but even a cheapie little Casio calculator has its scientific uses. If I can get more info than I can start to figure out exactly where the iDrive display fits on the Fun/Science spectrum (not that they're mutually exclusive). Temperature is super useful as a way to make inferences about suspension/alignment/chassis/tire dynamics, not to mention driving behavior. Is the TPMS as good as a Fluke pyrometer? No. Is it a snapshot of what the tire is doing mid-lap? It might be. I need more data. I could buy Cup2 Connects like medphysdave (Thanks by the way! Super useful data.) but this is WAY cheaper!

...and it potentially adds knowledge to the community... even if that knowledge is that the tire temp readout is garbage.

So what are your tire temps? Measured vs reported.

Thanks again everyone!

I agree it a useful tool / fun, but some folks get hung up about +/- 1deg like its really significant.

If you use it as a reference value rather than absolute it is more useful I feel. Eg, last lap it was 35deg, this lap its 38deg, the actual temp doesn't matter whether it's tyre air temp or wheel temp or tyre carcass temp, but rather how it's changed that matters. (if that makes sense?)

My front curbside is always 2deg higher than the rest, even when cold and as they get warm is gets 3 or 4 deg higher, so I just put that down to measurement error and that's ok as I know that and can spot if it varies from that difference.