Solution for Adding Additional Sensors to TST TPMS System

Updated 05/15/2025 | Published 05/05/2025

Products Featured in This Question

TST TPMS for RVs - Color Display - Signal Booster - 4 Flow Through & 2 Cap Sensors

(377)

$453.00

Replacement SE2 Cap Sensor for TST 507 Series

(29)

$54.00

Question:

I have a TST color TPMS system on my motorhome. I would like to add sensors for my car I tow behind — 5 sensors for including the full-size spare, internal or else small enough not to stick out past the rim so I don’t break a metal valve stem while accidentally scrubbing a tire on the curb What are my options? The official TST-branded internal ones are expensive and come only in 4- or 6-pack, not 5. Also I worry that the steel straps for holding them on will cut through the paint on my steel rims and invite rust. Are there any less-expensive sensors that are compatible?

asked by: Adam

Expert Reply:

Hey Adam, we have the replacement SE2 cap sensor part # TST47FR that will work with what you have and is pretty small so it wouldn't stick out far enough to cause you any issues or problems with curbs. These are sold individually too so you wouldn't have to order more than you'd need. How do you like the TST system so far?

expert reply by: Jameson C

Adam

5/6/2025

Thanks for the info about cap sensors. That looks more reasonable than the big flow-through sensors for a car with small wheels. > How do you like the TST system so far? The TST system does its job. I'm in love with having a TPMS but I'm not in love with the TST in particular. (Note -- I didn't buy the base system from etrailer, it came from elsewhere) Things I wish I'd known before buying: * The sensors can leak in mysterious ways. Of my 6 flow-through sensors, one of them loses 10 PSI over two weeks. Bubble test shows the leak is coming from between the valve stem and the sensor -- should be fixed by screwing it on tighter or replacing the O-ring. But neither of those helped. When I swap sensors to different tires, the leak follows the sensor. <head scratching how this can be> * It takes a long time (several minutes) after turning on, before the info populates from all the tires. * The color display with little green tire pictures doesn't change the color when there's a problem. I was expecting the tire icon on problem position to turn yellow (low pressure) or red (blown) but instead they just stay green. Meanwhile when it starts beeping the display keeps cycling through tires so you can't know how bad the situation is without taking your eyes off the road a long time to cycle through tires looking for the one with a problem. * If your tire falls off and rolls away while driving, the system will not notify you. I know this because taking the display unit out of range of the vehicle doesn't set off any alarm.

Jameson C.

5/6/2025

@Adam Wow that's a lot of great feedback! Yeah I can see how that's not the most ideal setup. Sounds like they should have though a little harder on what life with the system would be like and think about features that make more sense.

Adam

5/6/2025

@JamesonC For the cap sensor https://www.etrailer.com/Accessories-and-Parts/TST/TST-507-RV-S4.html / https://www.etrailer.com/Accessories-and-Parts/TST/TST47FR.html I see it also has the brass nut like my flow-through sensor does. Is this nut required for safety or only for theft prevention (that is -- if I just screw the cap on without the locking nut, is the cap going to unscrew itself and fly off while I'm driving?)

Jameson C.

5/13/2025

@Adam I would strongly recommend using the lock nut to hold the sensors on. Since they are heavier the lock nut does a better job preventing the sensor from working it's way off.