Please note this shot shows the TPM sensor and the steel band retainer. I was in the process of removing the extra band material as this is a 16" wheel. A larger wheel would need a longer band.
The other from TireTraker has external sensors that screw onto the end of your metal valve stems. Or as I did on the end of my dual tire extension hoses seen here.
I also had some TST external sensors that mount on valve stems and look very similar to the TireTraker brand sensors.
This is the final post on the direct comparison of different sensor location. I previously posted results HERE but there was a question raised as the internal system was one brand from TST and the External sensors were from TireTraker. We needed to learn if the minor differences were due to the different brand or the different sensor location.
To accomplish this I mixed the external sensor brands and used three external sensors from TST vs three from TireTraker. Here are the numbers.
Ambient was in the upper 80s to lower 90s for this part of the test.
Internal vs External TPMS test results
All temperatures are in °F and pressure in Psi
Temp. RF 102 LF 102 RRO 104 RRI 109 LRI 113 LRO 106
Press 69 70 82 84 84 86
TST External System
TEMP RF 86 RRI 84 LRO 86
Press 70 84 86
Temp. RF 108 LF 111 RRO 115 RRI 124 LRI 117 LRO 109
Press 70 71 84 87 84 87
TST External System
TEMP RF 79 RRI 90 LRO 82
Press 71 86 87
Tire Traker External System
TEMP LF 78 RRO 100 LRI 91
Press 70 82 83
Now I realize that reading the above doesn't make the differences and similarities obvious or even easy to see so here is a summary of the findings.
TST system External vs Internal pressure readings are essentially the same
TST system External temperature readings run 20F to 30F cooler than TST Internal temperatures.
TST system internal sensor pressure vs external sensor pressure readings Tire Traker are essentially the same
TST internal temperatures readings run 15 to 33 (average 25F) hotter than Tire Traker external temps.
Reviewing the above results and the results posted in the July 20 report and the two March reports from tests with Ambient in the 30s and 40s, it is my considered opinion that both TST and TireTraker systems provide similar numbers for inflation pressure and that external sensors report temperatures that are 20F to 30F cooler than internal sensors for both brands.
Given the above comparison on the data readings, I would consider these two systems a toss-up for reporting the temperature or pressure, as long as you remember that external sensors are being cooled by external ambient so will report 20F to 30F lower temperatures.
There are some differences between the two systems and some of these are subjective. I will cover these differences in a future post.