I am getting into supermoto here and would also like to be able to take it to the local flat track once and a while. What tires mount up to Sumo 17's or the stock wheels and are alright on a flat track surface?
I'm definitely not a flattracker, but am interested as well. From what I've noticed though, the flattrack wheels go for narrow profiles, so I'm thinking you are going to have better luck on the stockers (or maybe just at least finding a front 19 or 18 to match whatever the rear is on your bike). Like I said, I've just been starting to look into it a bit, so I'm definitely not even really a beginner yet, but someone ought to be able to help out!
I am looking at doing some TT/flattrack practice to get dirt time for SM and have been told with our track hear that sumpermoto slicks work pretty well and simulate what we race on. Noteur soil here blue grooves really quick, so in a laomier, moister or softer enviroment it may not work. I'll update you when I try it if I can still type!
Dirt track riders run 19" wheels front and rear. I think you will have a hard time finding any tires in 17", they may make them for mini classes not sure on that. Maxxis and Goodyear Eagles are the tires I'm familiar with as far as brands.
I am running avon rains to do tt. Did a couple races last year I run the rear backwards didnt do to bad, running a 160 on a 4.25 rim its not that great, good on the holeshot but a little scary on the corners would a 120 fit on the rear?
You def. want rains if you are running wider 17" tires.
I ran sportsman for a few races with my 21" front (dunlop dirt track tire) and stock 19" rear (maxxis dirt track tire). Then I changed the front to a 19" and my supermoto bike now runs dirt track rubber so i can do whatever I want with it. One day I might get 17" wheels for it but for now the 19" combo does the job. Just don't ride on muddy trails when it's snowing!! Doh.