Help: Fender sizing

[Bugged]

Thanks Maran, but I already have the wheels I will use and I already know the offsets of the wheel. I know I will need widened fenders, just how wide is the question.

More specifically I need to know how wide of a FLARED FENDER to get to fit my wheels. Kerscher website says I only need the 4cm wider flared fenders but IIRC my tires poked out over 2 inches. 4cm is a bit less than 2 inches.