dyno question

[udontknowme]

was hoping jerry or arlen or someone else with alot of dyno experience could chime in. was planing to put my dirtbike on pretty soon. is it critical i mount up a street tire or will the knobby still do fine ?

[jadleybray]

If you can maintain traction with the knobbie, your good.  For consistency sake, run the same setup each time you dyno, tire, gearing etc.  If you slip on the drum, there's your answer

[Jerry Hall]

was hoping jerry or arlen or someone else with alot of dyno experience could chime in. was planing to put my dirtbike on pretty soon. is it critical i mount up a street tire or will the knobby still do fine ?

I would mount up a new soft compound street tire.  The ideal dyno tire is a drag racing slick or a road racing slick.  A knobby on a 30 hp 125 does not even get enough traction to give repeatable runs in high gear and we find a lot of rubber dust behind the roller.  A 250 or 500 dirt bike will shred a knobby very quickly.  I will not test a dirt bike with a knobby.  It does not get the power to the roller and when the tires are slipping it is damaging the rollers.  8 years ago it was over  $14,000 for replacement rollers for my dyno