Can I run Dunlop metric D404's on a Sportster 1200C ?

 

I will assume you have either a 19" or 21 front, and a 16" rear rims sizes. The answer is absolutely!! 100/90/19, 90/90/21 for front and 130/90/16 rear. newer Sporty's use a 150/80/16 rear.
I've used the 404 on my Dyna for years, much more grip than the stock 401's, and go just as far. Fastrider 124