Klaus, I am sorry you are wrong. It is pretty clear if you drive hard on over inflated tires that you have far less traction. In an emergency - such as when raining you will slide and hydroplane more easily. There is not a constant, or linear function between pressure on the road and control.
Under normal rolling there is no motion at all of the tire on the pavement - except the rubber squirms around on the road as the rubber is pressed and lifted from the road - it is a situation of static friction. If you have less material in contact, then side loads overcome the static conditions and kinetic friction reigns which is at least an order of magnitude less. When a tire is sliding it is a very dynamic situation with the tire rippling and gripping and releasing, in a complex and changing manner. You can regain control ONLY because static friction is reasserted. Because there is such a difference in between static and kinetic friction the transition can be violent. A good handling car tire, holds the tread on the road so that it can exist in a dynamic function where some of the contact patch is slipping and some is static. The squealing you hear is the sound of this - some of the tire is always gripping - some is slipping when in the boundary condition. You can seriously mess this up by inflating improperly. Highest efficiency is always at odds with safety and controlled handling during spirited driving or emergencies. One primary detriment to control is the tire being very tight and inflexible - over inflated. There is a lower limit also where the rim is holding a tire whose structure is no longer stable - it is wrinkling and hopping instead of the tire staying flat (deformed properly) as designed to do. Mike On Tue, Nov 11, 2014 at 5:56 PM, Klaus via EV <ev@lists.evdl.org> wrote: > Tire pressure is an important consideration. I have a theory that says > that the tire pressure should be slightly less than the pressure that it > takes to deform the surface the tire is rolling over since it takes more > energy to deform most surfaces than to deform the tire. > > Some think that by increasing tire pressure that I reduce traction due to > less surface area on the road. Well, in some situation maybe yes, but no. > The coefficient of friction between two give materials is a constant. In a > low tire pressure situation there is greater surface area in contact with > the road at a lower pressure. In a high tire pressure situation there is > less surface area in contact with the road but at a higher pressure. I've > not done that analysis but I believe that the amount of force it takes to > break traction is basically the same for both situations. > > I run 115 psi in my road bike tires, 43 psi in my car tires, 7psi in my > electric ATV tires, 25 to 45 psi in my mountain bike tires and 4 to 15 psi > in my fatbike tires. My theory seems to hold true when riding the road > bike from asphalt to the lawn compared to doing the same on the fatbike. > Oh, and both have great traction in both environments. Even when > backpacking with my hard soled hiking shoes, walking on the harder part of > the trail takes less effort than walking on the soft part of the trail. > > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.evdl.org/private.cgi/ev-evdl.org/attachments/20141111/da4a2f56/attachment.htm> _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
