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What Do Tire Ratings Mean
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Tire Numbers Explained
Understanding Tire Ratings
If you've watched the first of these two videos (Tire Rating
Nomenclature) then you probably know what each of the tire attributes are. This page explains
each attribute in greater depth. As always if you have questions, stop by or contact us
and we'll make sure your questions are answered.
Tire Rating Quick Reference Guide
| Attribute |
Importance |
| Tire Width |
Wider tires mean more contact with the road - since tires are round and only a small portion of
the rubber actually touches the road, a good way to add more traction surface is by using a wider
tire. However, the vehicle must be engineered for this - otherwise the tire will rub the body pieces
in the wheel cavity. Be mindful that Infinitis (which are mostly rear-wheel-drive) often use
"staggered" wheels, meaning that the rear tires are wider than the front ones. This results in less
tire squealing or "burnouts" during acceleration. |
| Tire Profile Aspect Ratio |
The thickness of the tire's side walls are critical in determining the comfort of the ride and
the confidence when cornering. When a tire with a large side wall goes over a bump, the walls flex
outward to absorb the shock. However, when that tire is put through a hard cornering exercise, that
flex causes the car to feel like it is rolling from side to side excessively. Higher performance
tires have a thin sidewall for razor-sharp cornering, but give up some cushion to do this. Another
common reason for low-profile tires is the use of large diameter wheels for appearance. If the wheel
gets bigger, the tire has to get thinner - otherwise the wheel will rub because it doesn't fit in
the wheel cavity anymore. |
| Speed Rating |
Your Infiniti is designed for high performance - meaning it can go very fast. When traveling at
high speed, the wheels create a tremendous amount of centrifugal force on the tires. This force of
rotation can cause a tire with a low speed rating to delaminate and explode. Although you may never
need to drive at these speeds (please obey the law), it's typical that a decent tire is rated much
higher than the speed limits say you can go. |
| Radial Indicator |
"Radial" simply has to do with the construction technique used in making the tire. Radial tires
have essentially been the universal standard for modern automobile tires. |
| Tire Diameter |
It is generally accepted that larger wheels look more attractive on a car. Larger wheels mean
larger tires - and larger tires mean smaller side walls (see "Tire Profile Aspect Ratio"). One
interesting effect that smaller wheels can claim as a superiority over their larger counterparts is
that they accelerate better and get better gas mileage at normal city speeds. Why is this true?
Reach back into your memory to your last physics class - a smaller radius increases applied torque
(tau = r cross f). The drawback? Since smaller wheels have a shorter 'rollout' (the length of your
tire if it were a line instead of a circle), they can't sustain the same top speeds as larger ones -
because your engine can't spin any faster and small tires simply cover less ground. |
| Load Rating |
Where the Tire Profile Aspect Ratio indicates how tall the side wall is, the Load Rating
indicates the stiffness of the side wall. If you have a really heavy car and weak side walls, the
tires will bulge out and possibly buckle. What makes your car heavy? Lots of passengers, luggage,
and anything hooked up to the tow hitch. The factory-specified tires on your Infiniti are selected
to moderate tolerances; if you plan on towing horses with your QX56, check with us to make sure
you're got enough load rating. |
| Treadwear |
This is a pretty simple equation - tires that use harder rubber last longer than those built
with soft rubber. A long tire life can be the opposite of performance though - a really hard tire
doesn't hook up to the asphalt very well. A grippier tire also means less road noise - imagine what
it would sound like if our tires were made out of hard plastic! Since Infiniti is a performance
brand, expect our tires to take soft tires seriously; they'll wear out faster, but you'll have a
whole lot more fun doing it. |
| Traction |
Although this attribute is determined by stopping distance in wet conditions (shorter distance =
better rating), the concept of traction is simple: more grip means more safety and more fun. The key
factor in traction is tread pattern. The tread grooves channel away water and lock into those small
surface imperfections of the road. Traction and Treadwear go hand-in-hand. |
| Temperature |
Just like any other material (metal, ceramic, jell-o), rubber has an ideal temperature. Too hot
and it will melt; too cold and it loses it's flexibility and stickiness. As you drive you
accelerate, brake, and turn - all of these actions cause friction between your car and the road. You
must have this friction to do any of these three things (try driving on pure ice and see how far you
go) but this friction causes wear and heat. If excessive heat is added to the tire, the rubber
molecules get greasy and start to lose their ability to hold the road. |
Infiniti of Mission Viejo means Tire Expertise
Our experts are proud of their knowledge - it's why you come here:
to save time when maintaining your car. So why would you go to two different businesses for
tires when Infiniti of Mission Viejo is your destination tire store? Our tire prices are incredibly
competitive and all include a Road Hazard Guarantee which every "discount tire" store charges extra for. Your
time is money - you're not saving anything by shopping anywhere else. Have your tires installed
along with your next service or maintenance - all in one fell swoop.
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