Potentially really stupid question - switching from 15-16" rims

[firebird1999us]

So I currently have stock 15" alloy rims and am on the cusp of needing new tires.. so I'm considering switching to some black 16" Enkei RPF1s. I've been really happy with my Pirelli P4s and have managed over 100,000-110,00 miles on at least two occasions.

The Pirelli's I have now are 195/65r15 and tirerack shows the diameter as 24.9"... tirerack shows the P205/55R16 P4 as being 25.1".

Am I crazy or would those tires essentially fit exactly the same or are tire height and diameter two different things I'm convoluting. It reasons if it's round a close diameter will indicate a close height.

I'm attempting to go up a size with rims and tires and hold off on any sort of suspension work for now without the car looking like a 4x4 or having some crazy gap between the fenders and the tires.