Below you will find tire information that ranges from general to detailed.

• Tire Care Packages
  • Regular
  • Super
  • Premium
• Tire Inflation
  • Underinflation
  • Overinflation
• Understanding the Numbers
  • Calculating Tire Dimensions
  • UTQG RatingM
  • Load Index
  • Speed Rating
• When Should I Replace My Tires?
  • The Law
  • Common Sense

Regular - FREE

• Professional Mounting
• Rubber Valve Stems
• Computer Balancing
• Torque Lug Nuts
• Lifetime Tire Rotation
• Manufacturer’s warranty against defects in materials & workmanship
  
  *Excludes Michelin Brand Tires Some Restrictions Apply

• Professional Mounting
• Rubber Valve Stems
• Computer Balancing
• Torque Lug Nuts
• Lifetime Tire Rotation
• Manufacturer’s warranty against defects in materials & workmanship
• Free Flat Repairs for the life of your tires
• If your tire cannot be replaced safely, it will be replaced for free for the first 25% of the tread, pro-rated for the remainder.
  
  *Excludes Michelin Brand Tires Some Restrictions Apply

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Premium - $12.50 per tire

• Professional Mounting
• Rubber Valve Stems
• Computer Balancing
• Torque Lug Nuts
• Lifetime Tire Rotation
• Lifetime Tire Balancing
• Manufacturer’s warranty against defects in materials & workmanship
• Free Flat Repairs for the life of your tires
• If your tire cannot be replaced safely, it will be replaced for free for the first 25% of the tread, pro-rated for the remainder.
  
  *Excludes Michelin Brand Tires Some Restrictions Apply

When vehicle manufacturers select a tire size for a vehicle, they evaluate the vehicle's gross axle weights, the anticipated use of the tire, and the tire diameter and width. Adjustments to these factors give the manufacturer a way to improve handling and appearance. This is especially true for performance tire sizes. The size selected is rarely limited to only one capability (i.e. carrying the vehicle's weight). The tire usually needs to have additional load capacity as well. This extra capacity is important because without it all of the tire's performance would be used up just carrying the weight of the vehicle and little would be left for durability at high speeds or responsive handling. For all vehicles produced since 1968, the original tires sizes and inflation pressures (including the spare) are listed on a vehicle placard. This placard can be located on:

• The driver-side door or door jamb (Ford vehicles on the rear passenger door jamb)
• Glove box or counsel door
• Fuel filler door
• The engine compartment

Additionally, some manufacturers also list the original tire pressure in the vehicle's owner's manual. If a car's inflation pressure has varied from that which was recommended by the manufacturer, it's likely that the tire's wear and performance characteristics have also changed.

If your vehicle's tires are underinflated by only 6 psi it could lead to tire failure. Additionally, the tire's tread life could be reduced by as much as 25%. Lower inflation pressure will allow the tire to deflect (bend) more as it rolls. This will build up internal heat, increase rolling resistance and cause a reduction in fuel economy of up to 5%. You would find a significant loss of steering precision and cornering stability. While 6 psi doesn't seem excessively low, remember, it usually represents about 20% of the tire's recommended pressure.

If your tires are over inflated by 6 psi, they could be damaged more easily when running over potholes or debris in the road. Higher inflated tires cannot isolate road irregularities well causing them to ride harsher. However, higher inflation pressures usually provide an improvement in steering response and cornering stability up to a point. This is why participants who use street tires in autocrosses, track events and road races, run higher than normal inflation pressures.

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Width X Aspect Ratio = Section Height X 2 = Combined Section Height + Wheel Diameter = Tire Diameter

Example...205/60R15 85H or 205/60HR15 205mm x .60=123mm x 2=246mm + 381mm (15") = 627mm or 24.69"

The first number is the width of the tire in millimeters, measured from sidewall to sidewall. To convert to inches, divide by 25.4 in the example above, the width is 205mm or 8.07".

The second number is the aspect ratio. This is a ratio of sidewall height to width. In the example above, the tire is 8.07" wide; multiply that by the aspect ratio to find the height of one sidewall. In this case, 205 X 0.60=123mm or 8.07" X 0.60=4.84".

The last number is the diameter of the wheel in inches.

To figure the outside diameter of a tire, take the sidewall height and multiply by 2, (remember that the diameter is made up of 2 sidewalls, the one above the wheel, and the one below the wheel) and add the diameter of the wheel to get your answer.

The Department of Transportation requires each manufacturer to grade its tires under the Uniform Tire Quality Grade (UTQG) labeling system and establish ratings for treadwear, traction, and temperature resistance. These tests are conducted independently by each manufacturer following government guidelines to assign values that represent a comparison between the tested tire and a control tire. While traction and temperature resistance ratings are specific performance levels, the treadwear ratings are assigned by the manufacturers following field testing and are most accurate when comparing tires of the same brand.

Treadwear receives a comparative rating based on wear rate of the tire in field testing following a government specified course. For example, a tire grade of 150 wears 1.5 times as long as a tire graded 100. Actual performance of the tire can vary significantly depending on conditions, driving habits, care, road characteristics, and climate.

Straight-a-head wet braking traction has been represented by a grade of A, B, or C with A being the highest. In 1997 a new top rating of "AA" has been introduced to indicate even greater wet braking traction. However, due to its newness, this grade will probably be applied initially to new tire lines as they are introduced and later to existing lines which excel in wet braking, but had been limited to the previous top grade of "A". Traction grades do not indicate wet cornering ability.

Temperature resistance is graded A, B or C. It represents the tire's resistance to the heat generated by running at high speed. Grade C is the minimum level of performance for all passenger car tires as set under Federal Motor Vehicle Safety Standards. This grade is established for a tire that is properly inflated and not overloaded.

Using a P195/60R15 87S tire size as our example, the 87S at the end of the size represents the tire’s service description. A service description identifies the tire’s load index and speed rating. Service Descriptions are required on all speed rated (except for Z-speed rated) tires manufactured since 1991.

The first two digits (87S) represent the tire’s load index and are followed by a single letter (87S) identifying the tire’s speed rating.

P195/60R15 87S - The load index (87) is the tire size's assigned numerical value used to compare relative load carrying capabilities. In the case of our example the 87 identifies the tire's ability to carry approximately 1,201 pounds.

The higher the tire's load index number, the greater its load carrying capacity.

89 = 1,279 pounds
88 = 1,235 pounds
87 = 1,201 pounds
86 = 1,168 pounds
85 = 1,135 pounds

A tire with a higher load index than that of the original equipment tire indicates an increase in load capacity. A tire with a load index equal to that of the original equipment tire indicates an equivalent load capacity. A tire with a lower load index than the original equipment tire indicates the tire does not equal the load capacity of the original.

Typically, the load indexes of the tires used on passenger cars and light trucks range from 70 to 110.

Load Index	Pounds	Kilograms
71	761	345
72	783	355
73	805	365
74	827	375
75	853	387
76	882	400
77	908	412
78	937	425
79	963	437
80	992	450
81	1019	462
82	1047	475
83	1074	487
84	1102	500
85	1135	515
86	1168	530
87	1201	545
88	1235	560
89	1279	580
90	1323	600
91	1356	615
92	1389	630
93	1433	650
94	1477	670
95	1521	690
96	1565	710
97	1609	730
98	1653	750
99	1709	775
100	1764	800
101	1819	825
102	1874	850
103	1929	875
104	1984	900
105	2039	925
106	2094	950
107	2149	975
108	2205	1000
109	2271	1030
110	2337	1060

Using a P195/60R15 87S tire size as our example, the 87S at the end of the size represents the tire’s service description. A service description identifies the tire’s load index and speed rating. Service Descriptions are required on all speed rated (except for Z-speed rated) tires manufactured since 1991.

In Europe, where selected highways do not have speed limits and high speed driving is permitted, speed ratings were established to match the speed capability of tires with the top speed capability of the vehicles to which they are applied. Speed ratings are established in kilometers per hour and subsequently converted to miles per hour (which explains why speed ratings appear established at “unusual” mile per hour increments). Despite the tire manufacturer’s ability to manufacturer tires capable of high speeds, none of them recommend the use of their products in excess of legal speed limits.

Speed ratings are based on laboratory tests where the tire is pressed against a large diameter metal drum to reflect its appropriate load, and run at ever increasing speeds (in 6.2 mph steps in 10 minute increments) until the tire’s required speed has been met.

It is important to note that speed ratings only apply to tires that have not been damaged, altered, under-inflated or overloaded. Additionally, most tire manufacturers maintain that a tire that has been cut or punctured no longer retains the tire manufacturer’s original speed rating, even after being repaired because the tire manufacturer can’t control the quality of the repair.

Over the years, tire speed rating symbols have been marked on tires in any of three ways shown in the following examples:

• 225/50SR16
• 225/50SR16 89S
• or 225/50R16 89S

Each of these was an acceptable method of identifying speed ratings.

Early tires had their speed rating symbol shown “within” the tire size, such as 225/50SR16. Tires using this type of branding were not to have been produced after 1991.

Beginning in 1991, the speed symbol denoting a fixed maximum speed capability of new tires must be shown only in the speed rating portion of the tire’s service description, such as 225/50R16 89S. The most common tire speed rating symbols, maximum speeds and typical applications are shown below:

When Z-speed rated tires were first introduced, they were thought to reflect the highest tire speed rating that would ever be required, in excess of 240 km/h or 149 mph. While Z-speed rated tires are capable of speeds in excess of 149 mph, how far above 149 mph was not identified. That ultimately caused the automotive industry to add W- and Y-speed ratings to identify the tires that meet the needs of new vehicles that have extremely high top-speed capabilities.

While a Z-speed rating still often appears in the tire size designation of these tires, such as 225/50ZR16 91W, the Z in the size signifies a maximum speed capability in excess of 149 mph, 240 km/h; the W in the service description indicates the tire’s 168 mph, 270 km/h maximum speed.

Most recently, when the Y-speed rating indicated in a service description is enclosed in parenthesis, such as 285/35ZR19 (99Y), the top speed of the tire has been tested in excess of 186 mph, 300 km/h indicated by the service description as shown below:

As vehicles have increased their top speeds into Autobahn-only ranges, the tire speed ratings have evolved to better identify the tires capability, allowing drivers to match the speed of their tires with the top speed of their vehicle.

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U.S. coins can be substituted for a tire tread depth gauge as tires wear to the critical final few 32nds of an inch of their remaining tread depth.

Place a penny into several tread grooves across the tire. If part of Lincoln's head is always covered by the tread, you have more than 2/32" of tread depth remaining.

Place a quarter into several tread grooves across the tire. If part of Washington's head is always covered by the tread, you have more than 4/32" of tread depth remaining.

Place a penny into several tread grooves across the tire. If the top of the Lincoln Memorial is always covered by the tread, you have more than 6/32” of tread depth remaining.

According to most states’ laws (including North Carolina), tires are legally worn out when they have worn down to 2/32" of remaining tread depth. To help warn drivers that their tires have reached that point, tires sold in North America are required to have indicators molded into their tread design called “wear bars” which run across their tread pattern from their outside shoulder to inside shoulder. Wear bars are designed to visually connect the elements of the tire’s tread pattern and warn drivers when their tires no longer meet minimum tread depth requirements.

However, as a tire wears it’s important to realize that the tire’s ability to perform in rain and snow will be reduced. With 2/32" of remaining tread depth, resistance to hydroplaning in the rain at highway speeds has been significantly reduced, and traction in snow has been virtually eliminated.

If rain and wet roads are a concern, you should consider replacing your tires when they reach approximately 4/32" of remaining tread depth. Since water can’t be compressed, you need enough tread depth to allow rain to escape through the tire’s grooves. If the water can’t escape fast enough, your vehicle’s tires will be forced to hydroplane (float) on top of the water, losing traction.