Originally Posted by JonathanJ

Ok , quick calculation taking some assumptions , max rev 7000 , using std box with straight through top , so at 7000 rpm , wheel rpm is going to be 7000/4.7 = 1490 wheel revs /min

Tyre rolling circumference 63.75"
distance / min @ 7000rpm = 9498.75" = 2638.5 yards =1.5 miles a minute = 90 mph

Even at 70 mph you are going to be doing 5450 rpm , ok for lane bashing , but not much good for cruising anywhere , even down to the shops