Community Forums

The Ward Den · 04-04-2023, 02:07 PM

I know there are dozens of threads relating to everyone's favorite TPMS brand, but this is a question simply regarding the sensors.

Does it really make a difference if one gets the cap or flow through variety? I mean, if you need to adjust the air to the tire(s) does it really matter if you take off the whole cap sensor or just the little valve cap on a flow thru? Either way you are removing one item from each valve to add/remove air.

Below are a couple random internet images for the two types.

Rusty Kramer · 04-04-2023, 02:37 PM

I have a TST with Cap type sensors. If you are using rubber stems you for sure need cap type flow through are too big and heavy. Most trailers and autos you tow have rubber stems.

Seldom need to add air, cap type are lower cost. I read that some owners have had flow throughs leak. Not sure if that is a real thing or not.
One thing for sure, install a good reliable TPMS. coach and trailer/toad vehicle.

IcePyro · 04-04-2023, 02:56 PM

According to the website, the flow thru sensors require metal stems, the caps can be used on any stems, otherwise they are the same price, same functionality, just have to remove the stem caps if you need to fill the tires

emiddleb · 04-04-2023, 02:58 PM

I have a mix, flow-through on the metal-stemmed RV tires and cap-type on the two rubber-stemmed dolly tires. No leaks on either, all work equally well. I do like being able to add air without removing the sensors... works for me.

groveln · 04-04-2023, 03:59 PM

I ordinally was using 8 cap type with my TST 510 system & when I upgraded to the Color monitor TST 507 I switched to flow thru's. I just made more sense to me when having to adjust air if needed that taking the cap on & off a few times till you get the right pressure you want opposed to the flow thru's where you simply air up to your desired pressure & done...way easier! 10 years with TST now.

MSHappyCampers · 04-04-2023, 05:16 PM

I prefer the cap-type so there is no possibility of air leakage through the sensor.

edgewant · 04-04-2023, 05:17 PM

I have a Tire Tracker TPMS. The sensors are cap type and don’t weigh much. But I’ve had two rubber valve stems on my 2016 Ram toad (with factory TPMS sensors) fail.

I believe even the cap type sensors can cause issues with rubber stems. I’ve replaced the rubber stems on my Ram with metal stems after luckily avoiding any issues.

NMBluept · 04-04-2023, 05:29 PM

For me the flow thru sensors make a bit more sense in that in order to add air to the cap type sensors the anti-theft part requires a tool to loosen first. On the flow thru there is a simple valve stem cover to remove. I rarely have to add air - maybe annually so its not a huge deal. Of course if the anti-theft devices aren't used this is a moot point.
The TST sensors are priced the same for cap or flow thru, the flow thru are longer and protrude a bit on the front wheels. I've had the same flow thru system on 2 MH's for over 7 years and never had a leak from the sensors - those rear inner extenders are a different story. I removed the extenders a couple of years ago and haven't missed them.

Safe travels,

KenZ71 · 04-06-2023, 01:17 PM

For me Cap type did not bother with the anti-theft stuff. Stayed in multiple sketchy truck stops without issues.

I'm just spitballing - chances are if someone is that hard up to steel the sensors they can't afford the entire system or don't know what they are.

Warhorse6 · 04-06-2023, 01:26 PM

I use flow thru on the coach and caps on the toad. If a sensor is going to leak it’s because of the rubber gadget that meets the valve stem.

DADSDOGHOUSE · 04-06-2023, 01:47 PM

I am also trying to decide about a TPMS for my coach, I cannot understand why so many tire blowout stories say the TPMS did not alert until the blowout incident occurred, or even when the owners check thier tire pressures ever morning before leaving thier RV park. I can see using the straight cap and not the flow through cap, just extra weight to stress the valve stem, even if using steel bolt on stems.

CaptainGizmo · 04-06-2023, 02:09 PM

I've got input along these lines. Most will prefer the simple (non-flowthrough) cap for the same reason mentioned.

There are other cautions and I've produced a couple videos on this topic if you'd care to watch my channel at "RV Squared".

I've had many who've experienced failings of the rubber stem, due to the weight of the sensor.

Dennis C. · 04-06-2023, 04:28 PM

I’ve had the caps and the flow-through sensors. I prefer the flow through sensors. This is especially true if the security locking nut is in place. I also like the length of the flow-through sensor for my inner duals. It makes them very easy to manage.

Dodge Guy · 04-06-2023, 05:06 PM

I have the cap sensors and love them. Either way you are unscrewing a cap.
Any of the newer vehicles with OEM TPMS systems with the rubber stems have a reinforced brass inner piece so they will work fine with either sensor.