Minor tire repairs - nail in tread

[Puppethead]

Which do I trust? TPMS or my dial gauge? Gvilleguy mentioned his was off by 1-2 pounds. Do I just ignore it?

Since your gauge is measuring actual air pressure and the TPMS is using rotational speed to calculate pressure, they're two different methodologies and it's reasonable that they're different. Go by the gauge since it's actual pressure, assuming you think it's calibrated.

 

[TripleD]

Since your gauge is measuring actual air pressure and the TPMS is using rotational speed to calculate pressure, they're two different methodologies and it's reasonable that they're different. Go by the gauge since it's actual pressure, assuming you think it's calibrated.

Maybe I should have driven faster rather than just 25MPH around neighborhood.

 

[Rexsio]

That’s what old guy carry in SE . You can plug any tire when a screw , nail is small , if any thing is large you should use a patch by professional as long tire is in good shape to patch .

 

[Rexsio]

View attachment 15761 That’s what old guy carry in SE . You can plug any tire when a screw , nail is small , if any thing is large you should use a patch by professional as long tire is in good shape to patch .

Compressor ,plug kit ,tork wrench .scissor jack from Toyota a gage to check a pressure.I do this on road in 10 minutes

 

[insightman]

TPMS is using rotational speed to calculate pressure

If that's true, why does MINI bother to put a battery-powered, balance-disturbing, unsprung-weight-increasing device inside the tire rather than just using wheel-rotation sensors built into the car like my Honda Clarity does?

 

[ColdCase]

Well found this thread about TPMS. Just had a low warning and checked pressure. A little low but not as much as indicated by the display. Pumped up to 38/35 Front/rear and and then did reset and drove until it displayed 35/32 so 3 pounds less than what my gauge showed.
Which do I trust? TPMS or my dial gauge? Gvilleguy mentioned his was off by 1-2 pounds. Do I just ignore it?

The TPMS pressure reference is internal to the tire where a gauge is reference to atmosphere. The higher in altitude you drive the lower the TPMS pressure value will be than a gauge value. At higher elevations there can be a large difference, at sea level usually within a psi or two. Always trust a quality gauge as thats the true tire pressure relative to atmosphere and what you should be monitoring..

The sensors have a small battery so they use a battery conservation strategy that includes sleeping most of the time. They wake when there is enough rotation for a period of time and then transmits pressure readings periodically at an interval of 5 -20 minutes more or less. Thats why it takes driving above a certain speed for some distance and time for the car's computer to capture sensor IDs and data.

There is also a temperature sensor, accelerometer, and perhaps another one I don't recall off hand, in the TPMS sensor whether the car manufacture uses them or not. You sometimes find a head scratching TPMS alert because the pressure readings are fine. After checking with a sensors tester you find that the sensor is reporting a temperature sensor failure.

Some car manufactures make the TPMS more user friendly than others. Pacific rim vehicles have notoriously been lagging behind in technology and a PITA where Chryslers have been completely automatic since 2004 or so. BMW and Minis are somewhere in between. For some reason they require manual intervention to reset, but at least seasonal tire rotations don't require a dealer visit

 

[TripleD]

The TPMS pressure reference is internal to the tire where a gauge is reference to atmosphere. The higher in altitude you drive the lower the TPMS pressure value will be than a gauge value. At higher elevations there can be a large difference, at sea level usually within a psi or two. Always trust a quality gauge as thats the true tire pressure relative to atmosphere and what you should be monitoring..

Well, thank you ColdCase. Think that explains my low reading since we are a mile high here in Denver.

 

[ColdCase]

Oh, one more nit, once the initial process of registering the sensor IDs with the computer is complete, the car's computer can interrogate sensors for pressure readings, like when you start the car. The system needs to identify a low/flat tire before you drive off.

When a sensor does not respond to interrogations or is found to be on a different corner than expected, the fully automated computers will go through the registration process again. It will automatically pick up replaced sensor(s) or rotated tires. The manual computers just light up an alert. Its up to the driver to refer to the owners manual and dig through the menus to initiate the registration or otherwise fix the problem.