56 BMWcar
TECH TALK
SIDEWALL MARKINGS
Your tyre’s sidewall has a whole wealth of informati
on it, some of which is relevant and important to
you, some of which isn’t, but here we’re going to g
through all of it so there’s no mystery.
TRACK TYRES
These diff er hugely from road tyres, in that their pri
is performing well on track, usually in the dry and u
conditions. This means that engineers can design ty r
fewer inherent compromises than is the case with y
because the objectives are much simpler. The main g
track tyre has to do is provide grip; other factors suc g
noise levels and comfort are of no concern.
At the top end you’ve got slicks which are, obviou r
track use. They’re hopeless in the wet as they can’t
water, but there’s nothing to touch them when it co y
grip levels. The next step down from slicks will be w
that are still track-specifi c, but have a directional tre p
designed to help disperse water.
Finally, you have track tyres that will be optimised
but which are also fully road legal, allowing the car
to the circuit without the need to swap wheels onc y
of these are certifi ed for competition driving as wel
Some will have been designed with dry weather us
but will still able to deal with wet conditions, while
better all-rounders, with a greater number of groov
pattern that’s better suited to dispersing water. All, t g
very soft compounds for maximum grip.
Your tyre’s sidewall has a whole wealth of information
you, some of which isn’t, but here we’re going to go
These diff er hugely from road tyres, in that their primary purpose
is performing well on track, usually in the dry and under optimum
conditions. This means that engineers can design tyres with far
fewer inherent compromises than is the case with road tyres,
because the objectives are much simpler. The main thing that a
track tyre has to do is provide grip; other factors such as longevity,
At the top end you’ve got slicks which are, obviously, only for
track use. They’re hopeless in the wet as they can’t disperse
water, but there’s nothing to touch them when it comes to dry
grip levels. The next step down from slicks will be wet tyres
that are still track-specifi c, but have a directional tread pattern
Finally, you have track tyres that will be optimised for track use,
but which are also fully road legal, allowing the car to be driven
to the circuit without the need to swap wheels once there. Many
of these are certifi ed for competition driving as well as track days.
Some will have been designed with dry weather use in mind,
but will still able to deal with wet conditions, while others will be
better all-rounders, with a greater number of grooves and a tread
pattern that’s better suited to dispersing water. All, though, will use
1 Name of tyre manufacturer
2 Model of tyre
3 Tyre width in mm
4 Sidewall height as a percentage of width,
here 35% of 255mm
5 ‘R’ for radial tyre
6 Wheel diameter in inches
7 Load index, indicating the amount of weight
each tyre can support in kg
8 Speed rating, from N to Y, denoting the maximum
speed to which a specifi c tyre is rated, with Y
being the highest at 186mph
9 ECE mark indicating that this tyre meets
ECE standards
Indicates if tyre has an outward-facing sidewall
For directional tyres this shows in which direction
the tyre must rotate when mounted
Date of manufacture, with the fi rst two numbers
indicating the week of a specifi c year and the
second two, the year itself1 2 3 4 5 6 7 8 910
11
12