How Far Can You Push A "Donut"?

Discussion in 'The Champagne Room' started by SRT-Tom, Jan 9, 2017.

  1. SRT-Tom

    SRT-Tom Full Access Member

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    The February 2017 issue of Car & Driver had an interesting test of a mini-spare ("donut") on a Ford Mustang GT.

    The test was trying to determine how hard you can push a "DO NOT EXCEED 50 MPH" tire donut before you get into trouble.

    Surprisingly, the donut held up quite well in braking, skidpad and, to a lesser extent, acceleration tests. Ford's supervisor of Vehicle Dynamics Team, Jamie Cullen, stated the the "goal with a mini-spare is to come as close to the standard tire's performance and response as possible. Mini-spares use an aggressive compound and minimum tread depth to achieve those results." (Note- Some suppliers are known to use the same compound on their mini-spares that they use on superbike tires).

    Here are the tests summaries:

    Braking

    Full ABS braking from 70 mph with the spare on the left front was barely more dramatic than with four Pirelli P Zeros. There was a mild pull to the left but it only took one more foot for the car to stop (i.e., 173 ft.).

    Skidpad

    When fitted on the outside-front position, the spare reduced feel, response and grip, from 0.88g, with the P Zeros, to 0.84g.with the mini.

    Acceleration

    Zero to 60 mph was most adversely affected- from 4.8 sec., with the P Zeros, to 5.2 sec. with the mini on the left rear. It was interesting that the limited-slip differential attempted to rotate the tires at the same speed, despite a 2 inch diameter difference. Predictably, the result was less grip and more wheelspin.
     
  2. soonercruiser

    soonercruiser Full Access Member

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    I try not to "push the donut"!
    I try to savor the sugar on my tongue as long as I can.
    Then, wash down with some good coffee!

    :favorites37:
     
  3. SRT-Tom

    SRT-Tom Full Access Member

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    How long can you savor the taste of a donut before it goes '"flat?"
     

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