Accord Euro stock rim size.

[Crapdaz]

Stargazer, 225/40/18 is the right size. Thats what most people with 18" wheels are running on including myself. Check your calcs again, the diameter should not have increased by 16mm.

Sorry, didn't make it clear. I was going for 18x7.5 wheels (but will 18x8.0 fit a 2004 accord euro?)

yeh choose the right offset.

Between +40(lower) to +55(higher) will work. (Not the only offsets available though, but the range the euro would be suitable for)
+40 more likely to touch wheel arches at a higher ride height.
+55 sits inside wheel arch so has more room for lowering.

+40 will give you a flush look, and by having it further out will mean you will have more negative camber than someone who has a higher offset wheel.

Ingalls or any camberkit is a must when lowering.

hope this helps you even though it's all been covered....