Hi everyone,
Just a small update. Before buying the wheels I looked into the TPM (tire pressure monitoring) function of the Outlander and was not able to find a lot of info. I leave here my success story for future reference.
After 2014 every car sold in the EU has to have them. The PHEV runs fine with wheels without the TPM sensors, but will complain with a dashboard light and warning (quite annoying as it is always in your face). These are a small electronic device that sits on the inside of the air nozzle of each wheel and reports pressure and temperature. Each of these sensors has an ID which needs to be registered with the car's computer (so it knows it is reading its own tire sensors and not the car going by next to you)
If all you want is to change rims permanently, then you can just take the sensors out of the old ones and fit in the new ones.
If buying an extra set of rims, you have 2 options:
1) clone the existing IDs into new physical sensors. This way the car doesn't even notice that new wheels are installed.
2) get new physical sensors with new (different) IDs. The car allows for 2 sets of wheel IDs to be programmed in the computer (usually winter and summer tire sets). You can reach this selection menu in the configuration panel (it's a "1 - 2" selector with a wheel symbol near the end of the list).
I could not find a way to easily read the existing sensor IDs, so I just bought sensors with new IDs from ebay (second option above). These were TyreSure OE-R sensors, configured for the "Outlander 2014-OEP" (mine is the 2016 version). The actual link was this one, but it might die in the future:
http://www.ebay.co.uk/itm/TPMS-Sensors-4-OE-Replacement-Tyre-Valve-for-Mitsubishi-Outlander-2014-EOP-/162323345491?hash=item25cb39b053:g:nqUAAOSwo4pYVCwT
The box included the sensor IDs in a paper slip, but I don't think these are necessary for programming. The hardest part was finding a dealer willing to program these. It seems this is not very common in this country (we have mild weather - no need for a winter set). I talked with 4 different dealers and only one was willing to do it (had never actually done it, but were willing to try the procedure for the first time). It worked flawlessly. It's a simple procedure if you have the correct Mitsubishi tools (you plug a device to the diagnostic port below the steering wheel and activate the wheel sensors with another handheld device one by one - 10-15 minutes of work). It's a shame Mitsubishi does not include a user procedure for learning new IDs as some other manufacturers do.
Now I have the onboard computer programmed with both ID sets and can change the current set of IDs in the dash display. If you go the "clone IDs" way, you don't even need to do this as both sets have the same IDs, but you need to somehow be able to read the IDs of the current sensors (perhaps your tire change company has the gear for this).
If you live in the Lisbon area, I have only great things to say about the people at Univex (near Shelas - thanks guys!). It seems most other dealers in the region are mostly interested in the bread-and-butter no-hassle yearly maintenance fees (NOTE: I only called 4 different ones in the area so you might be able to find somebody else willing to do it). One of these other dealers said they would do it for 107 euros as it was a labor intensive procedure taking 1 or 2 hours. Do not buy this. It takes 10-15 minutes.
Hope this helps other people in the future.