3.0" tire on 18x2.5" rim?

Hey Guys,

I have this 18x3.0" tire on a 2.15" wide rim and it looks great but was thinking to go even wider with the rim to 2.5"
What do you guys think? is there a problem with going that wide?
I want it to look a bit more low profile with less tire deflection and most important, look cooler.
* These are dirt bike tires and rims...

I can't speak from experience with knobby moto tires, but based on my experience with bicycle and street motorcycle tires? The bigger rim would fit fine, cost you a bit of cush (but also let you use slightly lower pressure), and probably change the tire's turning and traction characteristics a little (likely better on pavement, less so on dirt). The bigger rim is likely to be significantly heavier, because wider rims usually go on bigger bikes.