1. What is the correct tire size for my vehicle?
To choose the right tyres for your vehicle you need to know the correct dimensions about them. You can check the manual of the vehicle's producer or your registration certificate. Also you can look the sidewall of tyres fit on your vehicle at the moment.
185 - this is the normal width of the tyre in mm
55 - profile - it's not a height in mm, but percent ratio of the width, it should be choosen precise
R - for Radial tyre, all passenger tyres at the present moment are radial
15 - size of the Rim diameter in inches
81 - Load index - how many weight can carry one tyre, it defines by table, in this case
H - Speed index - what is the maximum speed you can drive this tyre, here H means 210km/h
2. EU Tyre label description
In November 2012 a standard label for vehicle tyres was introduced in the EU. Based on three criteria it gives information about fuel efficiency, wet grip rating and noise levels.
Fuel efficiency - This label shows you how a tyre performs on fuel consumption -fuel efficiency is graded from A to G (rating D is not used for passenger cars). The difference between an A rating and a G rating could mean a reduction in fuel consumption of up to 7.5%. To put this in real terms, choosing A-rated tyres instead of G-rated tyres could save you more than 6 litres of fuel every 1,000 kilometres (based on an average consumption of 8 litres/100km)
Wet grip - This label shows how well a tyre brakes in wet conditions. Graded from A to G (ratings D and G are not used for passenger cars). In an emergency situation, a few metres can make all the difference. For a passenger car applying full brakes from 50mph, a set of A-rated tyres will brake up to 18 metres shorter than a set of F-rated tyres (braking distances may vary according to driving conditions and other influencing factors).
Noise - This label shows you the noise level in decibels of a tyre. The tyre is categorised in 3 classes illustrated by 3 waves: 1 black wave - Quiet (3dB or more below the European limit), 2 black waves - Moderate (between the European limit and 3dB below) and 3 black waves - Noisy (above the European limit)
3. Load and Speed indexes
On the sidewall of the tyre, next to size stay 2(3) digits and a letter (for example 91V). These are Load index and Speed index.
Load index - refers to the load-carrying capacity of a tyre, or how much weight a tyre can support. For example 91 response to 615kg support for each tyre at maximum air pressure.
Check well the load index according to producer's recommendation and weight of the vehicle.
Speed index - the maximum speed which your tyre is capable of maintaining. It is always represented by a letter (in the example above - V). In this case the letter V means 240km/h
Check well the speed index according to potential of the vehicle and your driving stile.
Here are the most popular speed indexes:
M - 130km/h
Q - 160km/h
T - 190km/h
V - 240km/h
N - 140km/h
R - 170km/h
U - 200km/h
W - 270km/h
P - 150km/h
S - 280km/h
H - 210km/h
Y - 300km/h
Z speed index appears for tyres with speed limits over the maximum. For an example when the size of the tyre is 285/35ZR19 (99Y) and 99Y is in brackets this tyre could be drive with more than 300km/h
4. Explanation of Special marks
Right next to the size and load and speed index some tyres have other marks with additional information:
XL (RF) - eXtra Load (or ReinForced) - tyre that allows higher weight than a normal one for the same size. For example you can have size 205/55R16 91W or 205/55R16 94W XL. In first case that tyre can carry 615kg while the second one - 670kg.
Run-flat - tyre which allows you to continue driving in case of low pressure as a result of perforation or other issue. To ensure safety in that kind of situation, the Run-flat tyre must maintain certain speed and distance parameters - max 80km/h for 80km.
The different companies use different marks about the run-flat technology - RFT or EXT for Bridgestone, SSR is used by Continental, ROF for Dunlop and Goodyear and ZP used by Michelin.
M+S - mud and snow - this mark is commonly found on all-season tyres, with self-cleaning tread and average traction in muddy or snowy conditions. Still it doesn't means a tyre with such a mark is a winter tyre. All winter tyres carry this mark, but the reverse is not true. The mark M+S is the result of autonomous classification by manufacturers. It can also be found on summer off-road and all terrain tyres.
FR (MFS, FP, FSL) - flange rim protection - it's additional layer of rubber on the sidewall of the tyre made to protect the rim from damaged contact with the curb. Usually tyres with height ratio under 55 have this rim protector, but it's not obligatory. It's possible for one tyre model to have variants with or without rim protector on the same size.
Other special marks, which can give you more information about the tyre are:
BSL - Black Serrated Letters
BSW - Black SideWall
OWL - Outline White Lettering
ORWL - Outlined Raised White Lettering
RBL - Recessed Black Lettering
RWL - Raised White Lettering
TL - TubeLess tyre
TT - Tube-Type, tyre must be used with an inner-tube
outside (exterior, side facing outwards) - for asymmetrical tyres, indicate how tyre should be mounted
arrows - for tyres with direction, shows direction of rotation
5. OE / Original Equipment
Original Equipment tyres, also known as OEM tyres or OE tyres, are tyres which are mounted on a new vehicle at the time of its purchase. The vehicle manufacturer selects these for optimised performance based on the characteristics of the vehicle.
Tyre producers use special OE marks for the different car brands:
* - BMW
AO, AOE - Audi
"B" in a circle, B, B1, BL - Bentley
C1 - Chrysler
F, K-1, K-2 - Ferrari
H-0, H-1 - Honda
H - Hyundai
J, "J" in a circle - Jaguar
LTS - Lotus
MGT - Maserati
MC, MC1 - McLaren
MO - Mercedes
MOE - Mercedes Extended runflat
N0...N6 - Porsche
R01, R02 - Audi Quattro
VW - Volkswagen
6. DOT Information
DOT code (coming from the Department of Transportation) is a mark on the tyre, which contains specific information about, amongst other things, where and when the tyre was manufactured. For the end user the most important part of this code is the date of production.
They are four digits (for example 4415) as the first two refers to the week of production and the second two - the year. In this case 4415 means - the 44th week of 2015
!!! All of the biggest manufacturers as Bridgestone, Continental, Dunlop and Goodyear, Michelin and Pirelli guarantee the quality of the tyres for a period of at least 5 years from the date of production, when they are preserved in optimum storage conditions (temperature, humidity, position etc.) !!!