I have some extra rear valances if you're looking to buy some
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I looked on Tenzo's website and I don't even see 19s offered for that wheel. I can say from having fit 19s on a S15 that getting them to look right on a S-chassis takes a lot of work, and you'll have some rubbing issues if you are tucking wheel - which is basically what is needed for them to work, haha.
I think a 19/19 or 18/19 set up can be pulled off with SUPER aggressive aero, but stock body, mild/OEM aero should stick with 17/17, 17/18, or 18/18 IMO.