Japanese wtf car

[CaL DaVe]

There's also more friction from the extra tire surface on the road.

<< has never understood why:

Force of Friction = fiction coefficient X normal force

Where is surface area in the equation? Why would fatter or more tires provide more traction?

[BobRobertson]

Force of Friction = fiction coefficient X normal force

Where is surface area in the equation? Why would fatter or more tires provide more traction?

Then why are race-car tires universally wider and larger than "normal" tires, specifically to provide more contact surface area?

I am not disagreeing with you, just pointing out an apparent contradiction to the strict equation. After all in theory, theory and practice are the same. In practice, they're not.

As a motorcycle rider, I cannot tell you if it is just smaller tires, or lighter weight, that makes a bike less sure footed than a car. Just that it happened.

[Sam Gunn (since nobody got Admiral Naismith)]

Tandem wheels worked on this car: http://www.youtube.com/watch?v=dchPW55k6pk

[CaL DaVe]

Force of Friction = fiction coefficient X normal force

Where is surface area in the equation? Why would fatter or more tires provide more traction?

Then why are race-car tires universally wider and larger than "normal" tires, specifically to provide more contact surface area?

I am not disagreeing with you, just pointing out an apparent contradiction to the strict equation. After all in theory, theory and practice are the same. In practice, they're not.

As a motorcycle rider, I cannot tell you if it is just smaller tires, or lighter weight, that makes a bike less sure footed than a car. Just that it happened.

Yeah, this is kinda what I was trying to say. I don't get it. I wonder what makes the fatter tires work.

[Sam Gunn (since nobody got Admiral Naismith)]

Force of Friction = fiction coefficient X normal force

Where is surface area in the equation? Why would fatter or more tires provide more traction?

Then why are race-car tires universally wider and larger than "normal" tires, specifically to provide more contact surface area?

I am not disagreeing with you, just pointing out an apparent contradiction to the strict equation. After all in theory, theory and practice are the same. In practice, they're not.

As a motorcycle rider, I cannot tell you if it is just smaller tires, or lighter weight, that makes a bike less sure footed than a car. Just that it happened.

Yeah, this is kinda what I was trying to say. I don't get it. I wonder what makes the fatter tires work.

More surface area = larger contact patch = more real friction, so handling improves.

[Cognitive Dissident]

It's been a long time since I've studied friction (like, 15 years.)  This web page implies that the component of friction does not change with extra surface area, but the force of friction does...it also explains why treads work better than slicks (more surface mating with the road, a similar effect.)  There's probably a better explanation available.

http://www.worsleyschool.net/science/files/tires/andfriction.html

In addition:WRT multiple wheels, they're probably making up for less traction due to high unsprung weight by adding wheels, improving the odds that at any time enough wheels have positive contact with the road.  The tires are probably softer composites than usual too.

[Sam Gunn (since nobody got Admiral Naismith)]

It's been a long time since I've studied friction (like, 15 years.)  This web page implies that the component of friction does not change with extra surface area, but the force of friction does...it also explains why treads work better than slicks (more surface mating with the road, a similar effect.)  There's probably a better explanation available.

http://www.worsleyschool.net/science/files/tires/andfriction.html

In addition:WRT multiple wheels, they're probably making up for less traction due to high unsprung weight by adding wheels, improving the odds that at any time enough wheels have positive contact with the road.  The tires are probably softer composites than usual too.

Yup. 

I think another factor in the extra wheels is that the motors are actually in the wheel, perhaps they were having size constraints and to make the car faster decided to just add more wheels.  Just conjecture there.

[Cognitive Dissident]

I think you're right.  They might have only been able to get as much horsepower as they wanted by adding more motors, which also meant more wheels.  It's kind of a bummer if you think about it, because it probably means you'd have to buy a higher quantity of more expensive tires more often.  I'll bet they don't wear as evenly as tires on lighter rims with good springs either (I'm thinking, like a car with a shimmy.)

That, and there are a lot of hidden expenses in battery-operated cars, including the need to recycle batteries (yuck!)

Oh, and...long wheelbase probably means wide cornering, unless the rear wheels help.