UTQG stands for ‘Uniform Tire Quality Grading’. You may have noticed markings on the sidewall of your tyres for Treadwear, Traction and Temperature; these are UTQG ratings.
The UTQG ratings originated in America to allow consumers to easily compare the treadwear, traction and temperature capabilities of their tyres.
All SUV light duty construction and passenger tyres sold in America must, by law, have these ratings marked on the sidewall. Some tyres sold in South Africa do not carry the UTQG ratings so you may not have the information to compare a Cooper tyre to your current tyre’s quality.
Treadwear grades are an indication of a tyre’s wear rate. The higher the treadwear number, the longer it takes for the tread to wear down.
Treadwear grades are tested under controlled conditions using four vehicles fitted with test tyres that run in convoy. The vehicles repeatedly run a specified 640km road course for a total of 11,520km. Tread depths are measured every 1,280km and the measurements are averaged to give a projected wear-out life.
A ‘standard’ control tyre is assigned a grade of 100 and the treadwear rates of all test tyres are compared to it. For example, a tyre grade of 200 should take twice as long as the control tyre to wear out.
Traction grades are an indication of a tyre’s ability to stop in the wet. A higher grade should allow your vehicle to stop on wet roads in a shorter distance than a tyre with a lower grade.
Traction is graded from highest to lowest as AA, A, B and C.
Temperature grades are an indication of a tyre’s resistance to heat. Sustained high temperatures (for example, driving long distances in hot weather), can cause a tyre to deteriorate, leading to blowouts and tread separation.
EU tyre ratings
The EU tyre ratings are intended to give consumers more information on important safety and environmental information when choosing new tyres. It helps to compare tyres for wet grip, fuel efficiency and noise.
FUEL EFFICIENCY / ROLLING RESISTANCE
The energy lost when a tyre is moving is described as ‘rolling resistance’ and has a direct impact on fuel consumption and the environment. The tyres on a car can affect its fuel economy by 20%. The lower the rolling resistance, the tyre less energy is lost - reducing fuel consumption and CO2 emissions.
In the EU Tyre Regulation labelling, rolling resistance is expressed in grades, ranging from A to G. A is the highest performance tyre in its category, whereas G is currently the least performing. D is not used as a grade, helping to draw a clear line between the top and bottom three grades - the good and the bad.
Putting the scores into perspective, if fitting the worst scoring tyres in this category, you could end up using 6 litres more fuel every 625 miles than if you fitted ‘A’ rated tyres - so, potentially, ‘A’ rated tyres could save you enough in fuel bills to buy a new set of tyres!
WET GRIP / BRAKING PERFORMANCE
The wet grip label provides you with information on an important safety aspect of a tyre: its grip on wet roads. Tyres with excellent grip in the wet have shorter braking distances on wet roads, an important safety benefit when driving in rainy weather.
In the EU Tyre Regulation labelling, a tyre’s wet grip capacity is also expressed in grades from A to G, with A the highest wet grip performance. Like the fuel efficiency score, D is not going to be used as a grade. The difference in braking distances between each grade is roughly 3m - the average length of 1 car. Making the difference between A and G 18m, 4 car lengths! This distance could be the difference between being involved in a road accident or not.
NOISE EMISSION / EXTERIOR NOISE
A tyre’s exterior noise grading is expressed in decibels, accompanied by one, two or three sound waves. One black wave indicates the best / quietest noise level performance, whereas three black waves indicate the weakest / loudest performance in terms of tyre noise output.
Load Index and Speed Ratings
The Load Index is a numerical code associated with the maximum load a tyre can carry at the speed indicated by its Speed Category symbol under specified conditions up to 210km/h.
Using a 265/75R16 123Q tyre size as an example, the 123Q at the end of the size represents the tyre’s service description. A service description identifies the tyre’s load index and speed rating. The first three digits - 123 - represent the tyre’s load index and are followed by a single letter - Q - identifying the tyre’s speed rating.
265/75R16 123Q - The Load Index - 123 - is the tyre’s assigned numerical value used to compare relative load-carrying capabilities. In the case of this example, the 123 identifies the tyre’s ability to carry a maximum of 1550 kg (3417 lbs). The higher the tyre’s Load Index number, the greater its load-carrying capacity. The Load Index rating also represents the load-carrying capacity of the tyres when they are inflated to maximum PSI so the load-carrying capacity reduces as tyre pressures are reduced.
|Load Index||kg||Load Index||kg||Load Index||kg||Load Index||kg|
Speed ratings are based on laboratory tests where the tyre is pressed against a large diameter metal drum to reflect its appropriate load, and run at (ever-increasing) speeds until the tyre’s required speed has been consistently exceeded.
It is important to note that speed ratings only apply to tyres that have not been damaged, altered, under-inflated or overloaded. A tyre that has been cut or punctured no longer retains the original speed rating, even after being repaired.
|Speed Category Symbol||Speed km/h||Speed Category Symbol||Speed km/h|
PLY RATINGS VS LOAD RANGE
It is not the tyre that carries the load, but the air inside it. The tyre contains the air. To carry more load you require more air. The best way to increase load capacity is to use a bigger tyre or a tyre that can run at a higher inflation pressure. The tyre needs to be strong enough to handle the higher capacity. The traditional ways to define this are Ply rating and Load Range.
The load range/ply rating is branded on a tyre’s sidewall and identifies how much load the tyre is designed to carry at its industry specified pressure.
What is “Ply Rating?”
In the days of bias tyres, casing strength was built up by adding layer upon layer of cotton fabric. The layers were placed with the thread in each layer at an angle to each other. That added strength, because the tensions would be distributed throughout the layers of fabric. The Ply Rating used to refer to the number of layers of cotton.
Cotton was discontinued in tyres a long time ago. One of the major improvements was making plies out of nylon. Nylon is so much stronger that tyres were stamped with the words, “2 Ply/4 Ply Rating.” That meant there were only two nylon plies, but they were so strong the tyre was equivalent to one made of four cotton plies.
Ply materials continued to improve, especially with the introduction of steel ply materials and radial construction, making the old Ply Number less and less meaningful. And that resulted in the newer designation we use today, called “Load Range.”
What is “Load Range?”
It’s no longer the number of plies. What is different today is the strength of the steel cables in those plies or the number of cables per inch. Tyre manufacturers are now at the point where instead of adding more plies the strength of the casing is adjusted to achieve the desired load capacity.
The Load Range is depicted on the tyre by an alphabetical symbol which equates tyre thickness to a comparable ply rating.
|Load Range||Ply Rating|