Page 1071 - Xmo Strata - Bulletin Archive

As part of our discussions, Michelin advised us that they have carried out extensive research into the
effect of tread depth (specifically 3mm vs. 1,6mm) in the last decade and that the factors that impact on
tyre safety are much more complex than solely the tread depth remaining.

They advised that studies of accidents throughout Europe have shown some interesting data; (graphs
are available if required)

• The highest frequency for accidents is for vehicles with 5-7mm of tread depth. This is simply
related to the fact that the majority of vehicles on the road have tread depths between half worn
and new. When looking at accidents in the dry and damp/wet, there is no increased frequency
of accidents with tread depths under 3mm. Either in dry or wet conditions, and this covers
many accident types (rear end accidents, single vehicle and multiple vehicle)
• The majority of accidents on wet roads are when the roads are lightly damp, e.g. 0.5-1mm of
water depth. This is due to the fact that these are predominately the main conditions of wet
roads, e.g. a small amount of rain with normal drainage meaning the roads rarely have deep
standing water.

There are many factors which influence wet grip and performance, namely the compound design has a
large effect on wet grip, as even if the tread pattern can dry the road, the compound is the part that
actually generates the grip. Therefore they say that use of a Michelin (or other premium brand), where
extensive R&D research, keeps development and improved safety at the forefront of advances, is a
good way of ensuring improved safety as their products will offer class leading wet grip throughout
their life.

Tyre pressure maintenance is also critical, as the footprint generated by the tyre is influenced
significantly by its pressure. This coupled with the appropriate speed is significant in preventing
aquaplaning, as the depth of water, coupled with the downwards pressure (load) and shape of the
contact patch are primary influences in governing whether the tyre lifts or cuts through the water.

The current heavy rain and flood conditions can mean that the standing water level is higher than
normal, however I would anticipate drivers taking extra care in these conditions regardless of their tyre
conditions.

Michelin's position was (and still is) that there is no need to move away from the 1.6mm as stipulated
by law, but our decision is based on the facts established from a number of sources. Internally, tyre
pressures, tyre conditions and tread wear should all be picked up on our weekly vehicle checks to
ensure that we do all we can to keep the driver (and others on the road or site he is driving on) safe.

We are all a product of learning. Every skill we have; everything we know; everything we believe and everything we do has
been learned throughout the course of our lives. Some of us learn best by studying graphs and charts, some through visual
presentations, and some by reading detailed text books. It is important that we receive information in a format that works
for us as individuals! That’s why at Xmo Strata we use a variety of communication platforms such as bulletins, newsletters,
videos etc. However, if you feel there is a better way for us to share health and safety information, please let us know.
Ultimately, your safety is in your hands – but we will do all we can to keep you well informed!