I've seen a lot of combine "drivers" try to go fast to put on a show. lets "operate" the combine. lets do a good job, put the crop in the grain tank, not on the ground for next years seed. I have seen all colors going too fast because the operator doesn't know how to adjust it. I have seen lots of operators drive slower than they have to because that is how they have always done it. Your question is pretty broad. I have seen them go 18 MPH on the road. Yes on the road. Some farmers will road an 8 row head and 20 foot platform. Or did you mean in the fieldIJIJ I've been in 9500's at 6 mph and better. Now what kind of corn are you talkingIJIJ 100 bushel...200 bushelIJIJ like I said this is a pretty broad question.