Will 195/50R15 tires/rims work on my 2005 Civic Hybrid?

Congrats on your new car!! The SI tires are perfect for the 15" rims. I'd usually say if you're going 10mm wider, go 10 less on the profile (so it'd be 60 instead of 50). It's actually fine, the only reason why you'd want a higher profile tire would be for cosmetics ( low profile tires sometimes leaves a bigger gap between the wheel well and tire, and it's ugly). So, yes the SI tires/ rims will fit on your Hybrid. Hope this helps!!