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Thread: Mileage or Make?

  1. #21
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    Right then, does all this effect the" Mileage or Make" of the wheels?

  2. #22
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    As a previous oster said, mileage is not as important as years ago. A well maintained car, such as a Toyota, will last 300k if well maintaned. Make is the important factor as well as maintenance. Mileage is secondary. I know car dealers who operate on this basis.

  3. #23
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    Santa, I am sorry, but I have noticed you have posted this before and still don't understand where the idea comes from. If you watch the small animation on the right side of the wikipedia page, that mark only travels the same distance as the circumference of the tyre along the flat surface. Forget the 'moving' tyre, and just watch the revolution. There is no 'slippage', so the tyre never stops and restarts but runs in a smooth rotation. As to your plank on a roller, I don't see where you get a difference in movement between the plank and the ground. If the roller moves n along the ground, it must move n along the plank. Try it with a bit of pipe or tube and a ruler.

  4. #24
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    Quote Originally Posted by Santa View Post
    The 'wheel' is rotating, but a point on the circumference of the wheel describes a series of semi-circles with twice the diamete of the wheel.
    http://en.wikipedia.org/wiki/Trochoid
    Wikipedia is not always accurate is it?

  5. #25
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    How else to convince you guys. If the road is not moving, and the tyre is not skidding, it MUST be stationary at the point of contact. A point on the circumference of a wheel on a moving car is describing a series of arcs (as shown on the accurate wikipedia diagram). It does not go round in circles.

  6. #26
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    Santa, it is not stationary,it is constantly rotating. Please forget about the Wikipedia article, it is talking about a trigonometrical formula. Your wheels do not describe an arc, only the travel of the marked spot. That marked spot is part of a rotating, moving circle, not in relation to the circumference of your tyre on the road. If you take it to the extreme, then with every point of your tyre describing an arc, you would be bouncing down the road, or even possibly permanently airborne.

  7. #27
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    Quote Originally Posted by Santa View Post
    How else to convince you guys. If the road is not moving, and the tyre is not skidding, it MUST be stationary at the point of contact. A point on the circumference of a wheel on a moving car is describing a series of arcs (as shown on the accurate wikipedia diagram). It does not go round in circles.
    Only if you were aquaplaning might the tyres be stationary.

    Santa you are normally So clued up about everything, But on this topic of rotating tyres, I think you have been lead astray by an obtuse and probably inaccurate Wikipedia article ( which is probably not related to motor vehicles?)

  8. #28
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    Santa, it is not stationary,it is constantly rotating.
    The wheel itself is rotating, but we are talking about a point on the circumference of the wheel.

    lead astray by an obtuse and probably inaccurate Wikipedia article
    I would be more concerned if you could tell me in what way the article is wrong.

    Neither of you have explained how it can be that a piece of rubber, in contact with a road surface, can be moving. If a car is moving at 50mph, the top of the wheels are moving at 100 mph and the bottom at 0mph.

  9. #29
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    "none of you have explained how it can be that a piece of rubber, in contact with a road surface< can be moving."


    That is the key fact which makes vehicles move. The invention of the wheel was one of the most important discoveries or inventions of all time.

  10. #30
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    Santa, if the wheel is revolving, and the tyre is attached to the wheel, then every point of the wheel is revolving. Just get someone to drive a car at around a constant speed of 5mph, and walk alongside and watch. See for yourself.

    Dennis, do the same. It is called 'friction'. Although in the motoring world we think of it as 'traction'. The wheel is moving (revolving), but because the road surface is fixed, then motion of whatever the wheel is attached to is the ultimate result.

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