We all know the capability of an M3, and its varying electronic assistance programs. The driver concedes he lost control of the vehicle on a gentle right hand bend (we drive left side here), slight uphill, and appoints an approx. speed of 80kph (around 49mph) however credits his loss primarily to accelerating through the corner and passing over loose sand / gravel, the sand and gravel was confirmed due to local construction (I would best describe the sand as a minimal amount, partially on his lane, at most the left side wheels would have passed through/over the sand). Clearly even the gadgetry could not provide, and he subsequently collected a wooden light pole, rotated and then the helpful services of a mighty tree a few meters past the pole, needless to say the vehicle is no longer! Both front tires were borderline, however legal, both rears (as we know, rear wheel drive!) were totally illegal and showed very little tread, and even some canvas on the inner shoulder of the right rear. Obviously we have address the usual issue of excessive speed indications, however the insurers have asked that we consider this issue of the cause, or contributory cause of the loss of control due to the issue of the sand and the condition of the rear tires. Logically sand/gravel cannot be treated as water, as it cannot be dispersed as water is and would generally have the riding on marbles effect. Therefore, and somewhat logically, one argument could be made that tread depth (or the lack thereof) is irrelevant. However I also assume that there is an argument that tread depth may well assist in dispersion of the sand / gravel to some extent, however is this so where the electronic gadgetry exists, remembering that such aids as ABS are typically disabled on rally cars!. My question is thus; which is the strongest argument? Intuition suggests that tread depth must assist to some extent, hence the use of aggressive tread patterns on rally cars, however this is particularly applicable in that situation due to the give nature of the surface being driven on, hence my second query, how should this be considered where the medium is sand/gravel on asphalt? Your wise input is appreciated. Craig
You initiall suggest there is only a smattering of sand on the road, so why is there a need to disperse the sand. Trying going back a step and consider the progressive consequences of the contamination - a few shovel full of sand wold be unlikley to have more hana momentary influence, a light dusting may act as a lubricant between the tyre and road, whilst 'just' a bit more may actually act as a retardant trying to resist the tyres passing through it. Driving over each surface at differing speeds can also influence the outcome. What was the influence of the 50mph for that bend was it easily done or on the limit. With the deeper sand one would expect tread to be favourbale to no tread, even a small amount. In each scenario, one would also want to consider how visible it was to the driver to be able to take any avoidng action.
