TST 507 Comparison

[W7BE_Bob]

I installed the TST 507 TPMS on my 8 motorhome tires along with the existing Smart Tire system that has internal tire sensors that are strapped on the inside of the rim.

As I expected the 507 system readings are about the same for tire pressure and very inaccurate for tire temperature. The 507 sensors are of course mounted on the end of the tire stems and hence subject to the normal air flow near the rim. I would rate the PSI as 5 of 5, the temperatures as 1 of 5 and the manual as 3.5 of 5. Since PSI is the most important in my opinion my overall rating is 4 of 5.  

The attached results and include a temperature measurement of the tires sidewall for comparison. The PSI is accurate but the temperature is up to 45% low and the InfraRed (IR) readings confirm the very low PSI issue. I can provide more detail as needed.

TST’s response:

Quote

 

Thanks for the info Bob.

Just note that the TST systems read internal air temperature which will be different from side wall temperatures.

 

 

[Dr4Film]

I always set my tire cold psi's on my car and coach with my calibrated Accutire MS-5515B Truck and RV Digital Tire Gauge. Then with the Tire SafeGuard TPMS that I use I don't expect those 10 sensors to reflect the exact same psi's but I do expect them to be close and within a few pounds of the tire gauge. Once on the road and warmed up I look for significant differences of both psi and temperature within the complete set as that would alert me to a possible problem while taking into consideration the hot side of the coach and car, inner dual versus outer dual, etc.

Extremely useful tool that has performed outstandingly on all of my travels since 2012 when I first purchased the Tire SafeGuard after having a terrible experience with the Doran TPMS.

 

Edited November 13, 2020 by Dr4Film

[W7BE_Bob]

Agreeded and my tire PSI is set correctly and the TST 507 displays the cold temperature within 2 degrees as expected.

I'm in the somewhat unique position of having internal tire sensors to compare against and the PSI is the same for each tire on both monitors. I expected the temperature of the external sensor  to be lower - How could it not be when it's on a metal stem  which is subject to the surrounding cooling outside air and  there is virtually no air flow in the stem? What I didn't expect was for the external sensors to read up to 45% lower. 

I did expect the sidewall temperature to be less than the internall temperature and my hand on the sidewall and stem confirm. My summer time tire temperatures run much higher of course. 

The TST manual recommends not changing the temperature alarm with no explanation. I'm suspicous that they are well aware of the issue and just want the user to use the default setting.