Frequently Asked Questions

Alignment

Wheel alignment consists of adjusting the angles of the wheels so that they are perpendicular to the ground and parallel to each other. The purpose of these alignments is to maximize the tyres life, fuel efficiency and ensure that the vehicle tracks straight and true when driving along a straight and level road.   Severe impacts (hitting potholes or curbs) and worn suspension parts are the leading causes of misalignment.

All Season Tyres

Tyres designed to provide good traction in a wide variety of road conditions, including wet, dry and mud and snow. This design also limits the tyre’s performance in extreme conditions, or when compared to tyres built for a particular category.

Aspect Ratio

A term that describes a tyre’s height-to-width proportion. If a tyre’s sidewall height were 65% of its width, its aspect ratio would be 65. In the tyre size expressed as 205/65-15, the number 65 is the aspect ratio.

Balance

The state in which a tyre and wheel assembly spins with all its weight distributed equally. Wheel Balancing allows the tyres and wheels to spin without causing any vibrations.  This is done by checking for any heavy spots on the wheel-tire combination and compensating for it by placing a measured lead weight on the opposite site of the wheel from where the heavy spot is.

Bar

This is a unit of measurement for air pressure within tyres.

Bead

A round hoop of steel wires, wrapped or reinforced by steel cords, placed at the very inside of the tyre's diameter.

Bias Ply Tyre

A tyre manufactured such that the plies are laid at alternate angles less than 90 degrees to the centerline of the tread. These criss-cross plies give the tyre its strength, but generate heat during operation and limit the tyre's wear and performance.

Carcass

The tyre body beneath the tread and sidewalls; also called the casing.

Contact Patch

The portion of the tread that in touching the road during operation.

Cord

The strands of material forming the plies or layers of tyre. Cords may be made from fiberglass, rayon, nylon, polyester or steel.

 

DOT Markings

Each tyre has a required Department of Transportation number imprinted on at least one of its sidewalls. That number begins with the letters "DOT" and may contain up to 12 additional numbers and letters.  The first and last digits are the most important for the tyre owner. The first two letters/numbers identify the manufacturer of the tyres.  The first two digits represent the week of production and the last two digits represent the last two digits of the year of production. So, 5114 as the last four numbers indicates that the tyre was produced in the 51st week of the year 2014.

Footprint

The full portion of the tyre that makes contact with the surface of the road.

Friction

The resistance of the tyre tread as it moves on the road; this is the force that causes the tyre to grip to the road.

Groove

The space between two adjacent tread ribs; also called tread grooves.

Hydroplaning

A skimming effect caused by tyres losing contact with a surface covered by water.  This results in loss of grip

Load Index

An assigned number ranging from 0 to 279 that corresponds to the load carrying capacity of the tyre.

M+S, M/S or M & S

Indicates that a tyre can reach particular standards for performance in mud and snow conditions.

Max. Inflation Pressure

The maximum air pressure to which a cold tyre may be inflated; found stamped onto the tyre's sidewall.

OE and OEM

OE means "Original Equipment" and refers to the tyres included with a new vehicle at the time of purchase. The vehicle's manufacturer selects these tyres to provide the optimal performance based on the performance characteristics of the vehicle. "OEM" stands for "Original Equipment Manufacturer."

Overall Diameter

The diameter of an inflated tyre without any load.

Overall Width

The distance between a tyre's outside sidewalls, including lettering and designs.

 

P Metric

Uniform designation of tyre sizes in metric measurements originally introduced by American tyre manufacturers in 1977. Commonly called "P-metric series." A typical P-metric tyre size is P215/70R-15.

Placard

A small label typically located on the edge of the driver's door or inside the glove compartment of a vehicle. A placard contains information on the vehicle such as the manufacturer's recommended tyre inflation pressure.

Plus-Sizing

A practice allowing drivers to customize the appearance and performance of their vehicle by mounting lower profile tyres on larger diameter wheels. One-inch greater wheel diameter is referred to as plus-one, two inches is plus-two... and so on. Using a lower profile tyre with a greater diameter rim allows the overall diameter to remain about the same.

Ply

A rubber-coated layer of fabric containing cords that run parallel to each other; extends from bead to bead and goes between the inner-liner and belts of tread.

Ply Rating

This indicates the load carrying capacity of the tyre in terms of its construction. A "C" indicates the tyre has a 6-ply load carrying capacity. The tyre is not actually built with 6 plies, but contains one or two plies of equivalent strength. A "D" is an 8-ply rating, and an "E" is a 10-ply rating. If there is no letter, the tyre has a standard 4-ply rating.

PSI

Pounds per Square Inch. This is the standard unit of measurement for air pressure within tyres.

Radial Ply

Tyre construction where the cords in the body run at 90 degrees to the centerline of the tread.

Rim Width

Distance between the two opposite inside edges of the rim flanges.

Rolling Resistance

The force required to keep a tyre moving at a constant speed. The lower the rolling resistance, the less energy needed to keep a tyre moving.

Rotation

Moving tyres from side to side or front to rear on a vehicle in a prescribed pattern to achieve uniform wear on all tyres. Rotations should be performed regularly every 10,000 KMS

Shoulder

The part of a tyre where the sidewall and tread meet. Certain tyre design features shoulder blocks for better traction.

Sidewall

The part of the tyre between the tread and the bead.

Size

An expression that defines a particular tyre in terms of its width, height, rim diameter, aspect ratio and construction type. 225/50-R17 expresses tyre size using the metric system.

Speed Rating

Speed rating represents the maximum speed your tyre is capable of maintaining.  It is always represented by a letter. Take a 195/65R15 87S tyre- The Speed rating here is represents by the Letter S which translates to the tyre’s ability to maintain speeds of up to 180 km/h.

Tyre Pressure Monitoring System (TPMS)

TPMS is an automated system that monitors the air pressure in a vehicle's tyres. When air pressure in one or more tyres drops 25 percent or more below the correct pressure, a warning alerts the driver.

Traction

The friction between a tyre and the road surface; the amount of grip provided.

Tread

The part of the tyre that comes into contact with the road. The tread type is distinguished by the design of its ribs and grooves

Tread Depth

The distance measured in the major tread groove nearest the centerline of the tyre from the base of the groove to the top of the tread.

Treadwear Indicator

Narrow bands, sometimes called "wear bars", that appear across the tread when 2/32" of tread remains.

Tread Width

The width of a tyre's tread.

UTQG (Uniform Tyre Quality Grading)

A tyre information system that provides consumers with ratings for a tyre's traction (AA to C) and temperature (A to C)

Valve

A device mounted in the wheel that lets air in or out of the tyre. Valves include caps to keep out dirt and moisture and a valve to prevent air from escaping.

Speed rating represents the maximum speed your tyre is capable of maintaining.  It is always represented by a letter. Take a 195/65R15 87S tyre- The Speed rating here is represents by the Letter S which translates to the tyre’s ability to maintain speeds of up to 180 km/h.

It is recommended never to downgrade the speed rating of your tyres. This may result in poor handling and unpredictable steering.  However, if you want better cornering response, there is no problem installing a higher speed rated tyre on your vehicle.

Never mix and match tyres with different speed ratings on your vehicle. This will cause serious problems with the handling of your vehicle.

 

Load index represents the tyre’s load carrying limit.  Take a 195/65R15 87S tyre- The load index 87 identifies the tyres ability to carry approximately 545 Kilograms.  The higher the tyre's load index number, the greater its load carrying capacity.

It is not recommended that a tyre with a lower load index than the Original Equipment tyre be installed in any vehicle.  You must always replace you tyre with a tyre of equal or higher Load Index rating.

 

 

Uniform Tire Quality Grading System (UTQG) rates tyres on their treadwear, traction performance, and temperature resistance.  All tyres sold in the UAE must carry a smart RFID tag affixed to them which also displays these characteristics.  These are also found on the sidewall of most passenger tyres, with the exception of winter and light truck tyres.

Treadwear grade indicates how long your tyres tread will last in relation to other tyres. For instance, a tire with a grade of 300 will last twice as long as a tire with a grade of 150.   However, actual tire performance can differ greatly for many reasons, including driving style, climate, inflation pressure and weight vehicle is carrying.

The traction grade rates the ability of your tyre to stop on wet pavement.  Traction performance is given as AA, A, B or C, which you will find on the sidewall of your tire.  Tires with an AA grade stop faster on wet pavement than those with a B or C grade.  So AA is the highest rated while C is the lowest rates.  The traction tests do not test tyres for cornering, acceleration, driving at high speed or driving on dry roads and cover straight line braking only.

Temperature grades are an indication of a tyre's resistance to heat. Sustained high temperature (for example, driving long distances in the hot Arabian weather), can cause a tyre to deteriorate, leading to an increased chance of a blowout or tread separation.

From highest to lowest, a tyre's resistance to heat is graded as “A”, “B”, or “C”. As per Gulf Standards Organization and EMSA, The temperature grade of a vehicles tyre sold in the Gulf region must be “A” or “B”.

The energy lost when a tyre is moving is described as 'rolling resistance'.  This has a direct impact on fuel consumption of a vehicle as well as the environment.  The lower the rolling resistance, the tyre less energy is lost, reducing both fuel consumption and emissions.  

To help you make an informed decision, PitstopArabia.com makes the rolling resistance of every tyre, where possible, available to you.  Rolling resistance is expressed in grades, ranging from A to G. A is the highest performing tyre in its category; G is least performing.   

To put these scores in perspective:  fitting the worst scoring tyres in this category, you could end up using 6 litres more fuel for every 1,000 kms travelled, than if you fitted 'A' rated tyres.  There’s approximately at + 7.5% difference in rolling resistance between Grade A and G.

'A' rated tyres could actually save you enough in petrol cost to buy a new set of tyres and more!

These grades are neither applicable nor available for professional off-road tyres, temporary-use spare tyres, studded tyres, tyres used only for racing, tyres whose speed rating is less than 80 km/h and tyres whose nominal diameter is smaller than 254 mm or bigger than 635 mm.

A tyre's exterior noise grading is expressed in decibels (dB).   To help you make an informed decision, PitstopArabia.com makes the exterior noise rating of every tyre, where possible, available to you. 

Choosing a tyre with a good noise rating will minimize the impact of your driving on the surrounding environment.  Increase of noise of just a few decibels makes a significant impact.  The quietest tyres have a decibel rating of 68 or below.   The loudest tyres would have noise levels of 72dB and above.

These grades are neither applicable nor available for professional off-road tyres, temporary-use spare tyres, studded tyres, tyres used only for racing, tyres whose speed rating is less than 80 km/h and tyres whose nominal diameter is smaller than 254 mm or bigger than 635 mm.

The wet grip provides you with information on a key safety aspect of a tyre: its grip on wet roads. Tyres with excellent grip in the wet have shorter braking distances on wet roads.

To help you make an informed decision, PitstopArabia.com makes the wet grip rating of every tyre, where possible, available to you.

A tyre's wet grip capacity is expressed in grades from A to G, with A the highest wet grip performance. These are measured by braking in a car travelling at only 80 km/h. The difference in braking distances between each grade is roughly 3m - the average length of a car. This makes the difference between A and G, 18meters, which is 6 car lengths! This distance could be the difference between being in a road accident or not.

These grades are neither applicable nor available for professional off-road tyres, temporary-use spare tyres, studded tyres, tyres used only for racing, tyres whose speed rating is less than 80 km/h and tyres whose nominal diameter is smaller than 254 mm or bigger than 635 mm.