Service with Sarah

With spring break just around the corner, before you begin your road trip, double check to make sure your tires are safe and in proper condition for driving. I thought this would be a perfect time to re-post my blog about tire safety!

Coggin Nissan Atlantic is now featuring a “Best Price Guarantee” tire campaign being held yearlong! We service most makes and models! Contact our parts department for more details.

Have you ever wondered what magic trick automotive technicians use to determine if you need new tires; or what all those numbers on the side of your tire mean? Well you have come to the right place to find out!

However, I’m going to break the bad news now…there is no magic trick! But there is a way you can measure the tread on your tires with something that you can find under the couch cushions. Not crumbs…..a penny or a quarter!

Tire tread depth measurements are taken in 32nds of an inch (tread depth is the valley in the rubber that touches the road). In most states tires are considered legally worn out at 2/32”.

1. To determine your tread depth with a penny place the penny into the first tread groove with Lincoln’s head upside down. If part of Lincoln’s head is covered by the tread you have more than 2/32” of tread remaining.

 2. Now turn the penny around so the Lincoln Memorial is upside down. Place it in a tire tread; if the top of the Lincoln Memorial is always covered by the tread then you have more than 6/32” of tread depth remaining.

3. If you were lucky enough to find a quarter, turn Mr. Washington upside down and place him in the tread. If part of Washington’s head is covered by the tread you have more than 4/32” of tread depth remaining.

 4. Once you have determined the remaining tread depth in the first location, you can complete your measurement of each tire by placing the coin into additional locations. To detect even wear measure15 in apart around the tire’s central groove, as well as in its inner and outer grooves.

*Be sure your coin is at the lowest point of the tread depth, and Not on the “wear bar”.

North America is required to have indicators molded into their tread design called “wear bars”. Wear bars are designed to visually connect the elements of the tire’s tread pattern and warn drivers when their tires no longer meet min tread depth of 2/32″.

Now that you can determine how much tread is remaining on your tires lets decode the hieroglyphics on your tires side wall. Federal law requires tire manufacturers to place standardized information on the sidewall of all tires. This information identifies and describes the fundamental characteristics of the tire and also provides a tire identification number for safety standard certification and in case of a recall.To identify the characteristics of you tires, you may use the following guidelines below.

1. Passenger Car Tire
• Starting at the top left of the tire, the “P” indicates that the tire is for passenger vehicles, such as cars, small trucks, and mini vans.
2. Nominal Width of Tire in Millimeters
• The three digit number following the “P” gives the width in millimeters of the tire from sidewall edge to sidewall edge. In general, the larger the number, the wider the tire.
3. Ratio of Height to Width
• The following two digit number is known as the aspect ratio number, it gives the tire’s ratio of height to width. The lower the number the smaller or shorter the side wall of the tire is.
4. Radial
• The “R” stands for radial. Meaning that the tire is radial ply construction, which has been the industry standard for the past 20 years.
5. Rim Diameter Code
• The next Two digit number is the rim diameter in inches. A tire can only mounted on a rim of the same diameter.

*For tires with a maximum speed capability over 149 mph, tire manufacturers sometimes use the letters ZR. For those with a maximum speed capability over 186 mph, tire manufacturers always use the letters ZR.

6.    Load Index & Speed Symbol

• The next two- or three-digit number is the tire’s load index. It is a measurement of how much weight each tire can support. The letter that follows this number is the speed rating. The speed rating is the speed at which the tire is designed to be driven at for extended periods of time. (although this does not mean you should) The speed ratings range from 99mph to 186mph.

7.    Severe Snow Conditions

• The letters “M/S” indicate that the tire has some mud and snow capabilities.

8.    Tread wear, Traction, and Temperature Grades

• The tread wear number indicates the tires wear rate. The higher the tread wear number the longer the tires should last. Just make note that the tread wear grade is not in mileage, this is because there are many factors that come into play to determine how fast your tires wear. A few examples are driving conditions, maintenance, and environmental factors.
• The Traction letter indicates the tires ability to stop on wet pavement. The higher the tire is graded the shorter stopping distance you should have on wet roads. (as long as the tires have good tread depth remaining….remember the penny) Tire Traction is graded form highest to lowest as “AA”, “A”, “B”, and “C”. With “AA” being the highest.
• The temperature letter indicates the tires resistance to heat. The temperature grade is for a tire that is inflated properly and not overloaded. Excessive speed, under inflation or excessive loading, either separately or in combination, can cause heat build-up and possible tire failure. A tire’s resistance to heat is graded as “A”, “B”, or “C”. With “A” being the highest grade.

9.    Max. Permissible Inflation Pressure

• Every tire has a maximum permissible inflation pressure. The number on the tire is the maximum pressure the tire should ever be filled with. Not to be confused with what the tire should be inflated to per manufacture specifications. Nissan recommends filling tires to 35psi when tires are cold. Abnormal tread wear can be caused improperly inflated tires as seen in the images below.

To identify the proper inflation that meets all federal standards, read the guidelines below for assistance.

1. U.S. DOT Tire Identification Number
• The U.S. DOT identification number begins with the letters “DOT” on the tire, and indicates that the tire meets all federal standards. The two numbers or letters following “DOT” are the plant code from where the tire was manufactured. The last four numbers represent the week and year the tire was built.
• For example the numbers 2809 mean the tire was manufactured the 28th week of 2009. The other number remaining are marketing codes used at the manufacture’s discretion. These numbers are what is used to determine if a tire is part of any recalls produced by the manufacture.
2. Tire Ply Composition and Materials Used
• The number of plies indicates the number of layers of rubber-coated fabric in the tire. In general, the greater the number of plies, the more weight a tire can support. Tire manufacturers also must indicate the materials in the tire, which include steel, nylon, polyester, and others.
3. Max. Load Rating
• This number indicates the maximum load in kilograms and pounds that can be carried by the tire.

Please do not hesitate to contact me or one of Coggin Nissan on Atlantic certified team members with any automotive questions. We service most makes and models! If you’re in the need for new tires, you may contact one of our certified service advisor’s for more details on the “Best Price Guarantee” tire promotion! Or you can schedule an appointment online. Remember, we are always here to help!

Drive safe,

Sarah
servicewithsarah@cogginauto.com
Coggin Nissan on Atlantic
10600 Atlantic Boulevard
Jacksonville, FL  32225
(904) 418-6510