Published by MOT Llandudno, this must-read guide takes you through easy to follow steps to ensure your tyres perform as they should and keep you safe on the road.
Published by MOT Llandudno
wait until our MOT to be told we need new tyres? According to the
Driver and Vehicle Standards Agency (DVSA), between April 2015 and
March 2016, over 2 million class 3 and 4 vehicles (cars and light vans up
to 3,000 kg) failed their MOT due to defective tyres.
Dangerous and illegal tyres account for one in four MOT failures.
As the only point of contact with the road, it is important to understand
how the condition of your tyres can affect your vehicles safety and its
fuel efficiency and it is estimated that British motorists may be
unnecessarily spending up to £600 million on fuel because of incorrect
tyre pressures. In addition to reduced fuel efficiency, having incorrect
tyre pressure may reduce the longevity of your tyres. It can also affect
your cars road handling, increase the vehicles stopping distance and
consequentially, the likelihood of being involved in a road traffic accident
weather conditions, the road surface, your vehicle and the condition
of its tyres. Typical stopping distances, as published by the Highway
Code are as follows:
In wet weather, stopping distances are doubled, in icy conditions they are
multiplied by 10. If your tyres are worn to their legal limit of 1.6mm, your
vehicles stopping distance can be increased by as much as 60%.
Shockingly, statistics compiled by The Department for Transport (2014)
reveal that, where vehicle defects were a contributory factor to reported
fatal road accidents, 56% were due to illegal, defective or under inflated
If these statistics alone aren’t enough to get you running outside to check
your tyres, then we don’t know what is but, if you’re unsure of what to
check for, we’ve devised this useful tyre safety guide, so you don’t have to
across the central three-quarters of the tyre. The tread must meet this
requirement around the tyres’ entire circumference.
Checking your tyre tread depth is a task you should perform regularly.
Follow our simple techniques for a quick and pain free solution:
Most tyre manufacturers now produce
tyres with tread wear indicators. These are
small, raised ‘nodes’ that are evenly spaced
around the circumference of the tyre,
within the main tread grooves. If the tyre
has worn to a point that the ‘node’ is flush
with the outer tread, it means the tyre is
below its legal limit and needs replacing.
a 20p coin. Simply place the coin in the
main tread grooves of the tyre. If the tyre is
above the legal limit, the outer band of the
20p will be hidden from view, within the
tread of the tyre. If the outer band is
visible, the tread depth may be illegal and
the tyre may need replacing. It is important
to check several locations on each tyre as
they can wear unevenly, particularly if the
pressure is incorrect.
THE 20P TEST
method of checking the thread depth of
your tyres. There are variations in price
depending on the sophistication of the
model you choose. A manual gauge can be
picked-up for under £1 or, if you’re a gadget
type of person, a digital gauge (many
include a tyre pressure checker) can set
you back about £10. Either device will give
you a good indication as to how legal the
tread depth is on your tyres.
How the tread pattern of your tyre is wearing is a good indication as to
the overall health of your vehicles suspension components, the
alignment of your wheels and if the tyres are under or over inflated.
Abnormal tyre wear can occur for a number of different reasons, below
are examples of the most common problems to look out for:
quickly on the outer edges compared to
the central area of the tyre. Under inflation
causes a dip in the centre of the tyre
meaning the outer edge, and potentially the
wheel rim, are more susceptible to damage.
more worn if your tyres have too much air.
Overinflating causes the tyre to bulge in
the middle, meaning there is less surface
area in contact with the road, which not
only makes for an uncomfortable ride but
also reduces grip.
You should check your tyre pressures regularly to ensure they meet the
manufacturers guidelines. The correct tyre pressures for your car can be
found in your vehicle handbook, inside the fuel filler cap or on the
driver’s door sill. Alternatively, TyreSafe have devised a useful tyre
pressure checker on their website, all you need is your car make and
model. It’s also worth noting, when shifting heavy loads, your tyre
pressure will need increasing, recommended settings can be found in
your vehicle handbook.
is the lean of the wheel away from the
vehicle when viewed from the front, toe is
the direction the tyres point relative to the
centre of the vehicle. If the tyres are
excessively worn on the outer edge,
positive camber and/or toe-in are the likely
suspects. If the tread is worn on the inside
edge of the tyre then negative camber and/
or toe-out is the issue. With toe-in and
toe-out you may also feel a feathered effect
when running your hand along the tread.
don’t panic, a simple wheel alignment by a reputable garage should fix
the issue. Misalignment can happen when we accidently hit a kerb, drive
through a pothole, or it could be the result of worn suspension
components, whatever the reason, it’s definitely worth getting it checked
of the tread, or if you experience a tyre
wobble or vibration when driving over
40-50 mph, one or more of your tyres
could be out of balance with the others.
technician will place small weights at specific points around the edge of
the wheel to ensure that the weight of the wheel and tyre is even
around the axis. If a re-balance doesn’t fix the issue, then the problem
could be more serious, such as weakened struts or shock-absorbers,
your garage will be able to advise.
tyres. If debris becomes embedded in the
tread, it can work its way into the casing of
the tyre and result in a puncture. Remove
all debris and if you suspect any damage, no
matter how small, it’s advisable to get the
tyre checked by a specialist.
damage the structural integrity of the tyre
sidewall. If the sidewall becomes weakened,
air leaks from inside the tyre through to
the carcass creating a visible lump or bulge.
If you find a lump or bulge in your tyre
sidewall, it is unlikely that it will be
repairable so expect to have to replace the
necessarily mean it has to be replaced. In
some cases, depending on the severity, a
repair can be carried out. This type of
damage is often caused by that pesky
debris, or it may be just plain old age
weakening the rubber. When inspecting for
tears, cuts and cracks make sure to check
between the tread grooves. If you discover
nylon cords poking through any damage on
the tyre, the internal structure may have
been compromised so DO NOT drive the
vehicle without first changing the tyre.
TEARS, CUTS AND
The lifespan of a tyre cannot be determined by a single factor. Heat,
storage and the conditions of use all influence how tyres age but if your
tyres are approaching five years old, it’s advisable to keep close eye on
their condition and consider replacing them. To identify the date your
tyre was manufactured, and establish its age, a four-digit code is
imprinted on the tyre sidewall. Sometimes proceeded by ‘DOT’, the first
two digits of the date stamp represent the week of manufacture and the
second two digits signify the year of production. The tyre below was
made in the 6th week of 2013.
Signs of damage to a tyre, such as lumps, bulges, tears, cuts or cracks can
be extremely dangerous and may put you at risk from a tyre blowout. If
you are in any doubt contact a tyre specialist.
manufacturers handbook. The handbook may specify a different size for
the front and rear, but tyres fitted to the same axel must be of the same
size. Once you know the correct tyre size for your vehicle, check this
matches the size currently fitted, the tyre size will be printed on the
sidewall of your tyres.
Fitting an incorrect tyre size can result in an MOT failure!
tyre above marked 195, the measurement
across the tread from sidewall to sidewall
will be 195mm.
height of the tyre sidewall, expressed as a
percentage of the tyre width. For our tyre
above its 55, meaning that the profile height
of the tyre is 55% of its width.
wheel rim that a tyre can be fitted to. For
our example, the rim diameter is 16, so this
tyre will fit on a 16-inch wheel rim.
Miles Per Hour
Kilometres Per Hour
Legally, tyres of the same construction must be fitted to the same axel.
There are two basic types of tyre construction; radial and cross-ply, each
has its own unique set of characteristics:
construction of a radial tyre allows the
tread and sidewall to act independently,
giving flexibility, strength and greater
control over the direction of travel. The
majority of tyres manufactured today are of
vehicles that work in extreme terrain as
they have a rigid sidewall construction
which protects against sidewall punctures
from tree stumps or sharp rocks. A cross-
ply tyre has a relatively low speed rating,
meaning if you are travelling at motorway
speeds over a period of time, you could
experience a blow-out.
the sidewall. If there is an ‘R’ between the profile and rim diameter (as
shown in the diagram above), the tyre will be of radial construction, if
there is a – between these two elements, the tyre will be of cross-ply
of structure, the overall condition of the tyre, the size and the tread –
pattern, breadth and depth. Spare wheels and tyres are not checked
during the MOT process unless they are fitted to the vehicle. If, at the
time of MOT, for some reason you have a ‘temporary use’ wheel fitted
to your vehicle, the MOT test will be failed.
Vehicles first used on or after 1st January 2012 will also have their Tyre
Pressure Monitoring System (TPMS) checked during the MOT to make
sure it is still working. Your vehicle will fail its MOT if a TPMS warning
light is displayed on the dashboard at the time of testing.
pressure and, in some cases, the temperature of your tyres.
There are two types of TPMS:
sensors but detects low tyre pressure through
the wheel speed sensors of the vehicles Anti-
lock Braking System. When a tyre is low on
pressure, its rotational speed increases and it is
this difference between the rotational speed of
each individual tyre that the indirect TPMS
system recognises. If your tyres are all equally
deflated, the indirect TPMS will not detect any
difference between each tyres rate of
revolution so you will not be alerted to an
under-inflation problem. An indirect TPMS also
requires the vehicle to be driven before an
issue can be detected.
sensor that is able to detect any changes in
individual tyre pressure levels. A direct
TPMS may also provide tyre temperature
readings. This type of system tends to be
more accurate than an indirect TPMS as it
collects data straight from the tyre valves.
Cars manufactured after 2014 will generally
have a direct TPMS fitted.
tyre. If all four tyres contravene regulations, you could be slapped with
an enormous £10,000 bill. You will also be rewarded for your defective
tyres with 3 penalty points that will stay on your driving record for 4
years from the date of offence.
Now you know how important tyre safety
is, please don’t leave it to chance or until
your MOT, get out there and get checking.