Does anyone have experience with an aftermarket TPMS system that could relay actual wheel pressure to a smartphone or separate monitor---such as SteelMate?

 

I have a tpms I got off amazon, shows pressure and temp, but temp is c only, they are external sensors.
Which means it is the valve cap, no need to have a tire shop to install, and have a display mounted inside.

 

Do you have to take the sensors off to add air to the tires?

 

Yes, external tpms consists of 4 transmitting caps and a dash mounted receiver display. Probably not as reliable as OE but gives you more info. Very cool and affordable!

external tpms | eBay

 

Yes, have to remove to add air to tire.
Also when battery is dead, you can change battery yourself. Instead of paying a shop.
Keep some spare batteries around, they are cheap if bought on ebay, $2 apiece buy 3 get 2 free, energizer lithium, $6.50 apiece in town.
Definitely worth it for me to see the exact pressure.
They have been working good for me, has a warning light and alarm when a battery is low on sensors.
If anyone pulls trailers and has had a blow out on a trailer and k ow that pain, there are also setups for trailers and trucks and trailers, a booster antenna is added so the monitor can get the data from the senor farther away on trailers.

 

Something to keep in mind. Thanks. But I would prefer psi readings. James

 

Some also use apps on phone instead of a display screen.
I wanted the screen.

 

Which brand/model is it?

 

I see that at least some of these give readings in BAR and PSI, you choose in the set up. That plus temp is probably more than required but ...
They look a bit clunky and you probably need a wheel balance if you are particular about added weights on wheels.
Me I'll stick with the OEMs a little bit longer.