Thanks for the compliment. I suggest you save yourself the trouble and money and leave it alone.
I have 18" diameter rims with 3.5" width on the front and 5.5" on the back. Went with the 18" 'cause I wanted more rim and less tire showing. If you're paying big bucks for rims someone might as well see them.
The rear tire is a Metzeler 880 ME 180-55; the front is a 130-70.
I also like the fat tire look and made a fender but there are two things of which you should be aware;
1. for daily riding - when it rains you'll get real dirty.
2. the fender needs to sit at least 3.5 " above the tire and for me I don't like to have that much space between the tire and fender.
The 250 is nice but I don't think I would go above 200. Just my perference.