Tire Size Question

Jul 03, 2005 23 Replies

In that case you remember this.

"Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it."

This is Newton's First Law of Motion, which is essentially the same as Galileo's concept of Inertia. You do not observe this principle in the case of a vehicle, because rubber tires dissipate energy and there is friction in the wheel bearings and air resistance. These three factors have nothing to do with the mass of the wheel and tire combination. However, mountain bike tires will be filled to a lower air pressure than road racing bike tires, and so will dissipate more energy. The same holds for any larger than stock tire on a Jeep.

I have not done or seen any formal study, but I think that the main factor to consider when changing tires is to maintain the same rpm to road speed ratio. This is what we call "gear inches" in the bicycle trade. How far do you go for each turn of the crank? If you change this factor, you will change available power and economy, in many cases for the worst.

Earle

Awesome. Maybe I should have tried those 400x19s on my Bug. :o)

Earle

Hey Earle.... here's my take... F =3D MA.

And forever is a *long* time... don't forget about gravity waves, and magnetic effects.

And Bill... keep it up! I want to hear more about gear ratios and E =3D mc^2! __ Steve .

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