IME, Panaracers have been measuring on the narrow side recently. Mounting them on narrower rims, such as 15mm interior, keeps the profile narrower. When I mount the same tire on a rim with 18mm interior, the width is close to what is stated. I have never checked tire heights.
I have a set ov Vittoria Zaffiro Pro Control labeled as 30mm. But they measure a bit over 32mm on 18mm interior wheels.
I check widths only for clearance issues, not to check tire specs. I generally use the widest that will fit with at least 2mm of clearance at all points of possible contact.