How fat can you go in a rear tire without mods? I've seen other threads.

 

Depends on model year. I see you have 2017 DF. I'm not sure if there have been any changes in the last couple years, but lots of guys on other late model Dynas are running 200s.

 

200 is a tight fit on a Street Bob, Super Glide and Low Rider. Pretty sure there is a little more room on the Fat Bob and Wide-Glide.