What is the benefit of the 11.5" tire versus a 10? What does greater circumference do for corner speed? My initial thought is its just more rotating mass on the axle. I just started to run dirt last season after 19 years of sprint racing. I am learning a lot from threads like these.
My brain is programmed from asphalt where going from a 6.00 to a 5.50 sometimes picked us up a half a second when the track was really tight. Would the 11.5" tire give you the effect of more grip in low bite situations?
I have not been able to give these a good testing, but the way I am looking at it is more for high HP engines (in my case). That 9.5" tire on a 10" wheel is putting about 18% more tread on the track over an 8" tire. I also see an advantage in them being much easier to mount than having to stretch the sidewalls. Should work well in stock classes on momentum tracks. If I have my head on straight, these should give more speed at the same RPM as 11" tires, assuming the engine has the power to pull them. We're only talking about maybe 3" difference. I would also expect it to smooth the bumps just a little bit. I will have to weight them and see how much weight we are actually looking at. In the spring I also plan to video the tire in action and see what the sidewalls are doing in turns.
I don't think these would work as well in sprint racing were you slow down much more in turns. The extra weight will most likely take longer to get up to speed. Sorry, that probably didn't answer your question, but I am just starting to play with these myself.