• Admiral Patrick@dubvee.org
    link
    fedilink
    English
    arrow-up
    3
    arrow-down
    2
    ·
    5 months ago

    I wouldn’t think stopping distance would be noticeably impacted by less rolling resistance. My original “eco” tires stopped the same as the standard ones. They’re “eco” because they have less rolling resistance and are slightly lighter.

    Plus, with ABS, you’re not likely to lock the wheels up such that the decreased resistance would be significant.

    On slick roads would be my only concern, but a good and season appropriate tread should mitigate that.

      • Admiral Patrick@dubvee.org
        link
        fedilink
        English
        arrow-up
        3
        arrow-down
        1
        ·
        5 months ago

        No they didn’t.

        In a strictly technical / laboratory sense, maybe not. But in practice, they stopped just the same. I also slow down to a stop (regen braking is amazing) and don’t slam on my brakes at a stop light (like some drivers I routinely scowl at). And driving through the country and having to slam on the brakes when a deer jumps out (which was common where I lived), I noticed no appreciable difference in stopping distance between the two tire types.

        …huh? ABS has nothing to do with rolling resistance…

        ABS prevents the tires from locking up and skidding (anti-lock braking system, hence the name). Under normal driving conditions, it merely helps you maintain control, but on slick roads, locking up the wheels can skid you further than without it. So, no, ABS doesn’t directly relate to rolling resistance, but it’s part of a system along with the tires that contribute to stopping distance…which is what I was talking about.

    • Jrockwar
      link
      fedilink
      English
      arrow-up
      2
      arrow-down
      1
      ·
      5 months ago

      In a car with ABS, two sets of tyres with different grip will have a different point at which tyres lock up, with grippier tires locking up later and ABS letting the brakes bite harder before acting.

      Now a harder question is whether a tyre with less rolling resistance will be less grippy. All things equal, yes, it will. Tyres grip by deforming and creating friction in the contact patch, and the point of these tyres is to reduce friction.

      To make up for this, manufacturers use clever designs (e.g. where tyres can deform more under certain conditions) so that they can retain characteristics similar to tyres with more rolling resistance. Of course, everything in engineering is a compromise, which means that A) these tyres are more expensive because of the additional complexity and B) the design and materials science can only go so far and they have indeed slightly less grip; otherwise all the tyres would be like this.

      As an anecdote, Toyota sold the GR86 with Michelin Energy Saver tyres fitted as standard (in Europe at least) for “grip” reasons: they allowed the car to drift at really low speeds (some car journalists commented that it was remarkably easy to take roundabouts sideways at legal speeds).