Ford Mustang Wheel Fitment - One Size Does Not Fit All

Many wheels, both factory...        read full caption Many wheels, both factory and aftermarket, are not centered using the central wheel opening. Rather, the wheel is centered on the bolt pattern for optimum balance when installed onto the car. This is called being lug-centric. The problem is that many tire stores just use a cone and don't have the lug-plate fixtures shown here, which are used to center the wheel perfectly on the tire-balancing machine. If you're having trouble balancing your styled-steel wheels or Magnum 500s, check to see if your balance shop is using the correct centering fixture.

This is our project's Wheel...        read full caption This is our project's Wheel Vintiques wheel and Nitto tire mounted on the Hunter Road Force spin-balance machine inside Pit Crew's mobile tire truck. This state-of-the-art balancer even simulates the vehicle load using pressure from a roller. This replicates actual operating conditions for the most accurate balance possible. Notice the lug-plate in use on the wheel, too.

While the wheel and tire assembly...        read full caption While the wheel and tire assembly turn on the balancer, information regarding the state of balance is reported on the computer screen using Hunter's SmartWeight system. The machine then instructs the operator where to place the weights and describes how heavy they should be in order to correct the imbalance completely.

With most aftermarket wheels,...        read full caption With most aftermarket wheels, there is no provision for balance weight attachment as there is on factory wheels. The solution is these self-adhesive lead weights that can be applied to the wheel without damaging the polished or chromed surface. They are available in exacting increments down to 11/44 ounce, or 7 grams. The higher-quality weights shown in grams are much more accurate than the "chocolate bar" weight at the top of the photo. Craig Knarich of Pit Crew Tire also stressed the use of the proper lug nut for the wheel being used. He said aftermarket wheels often come with the wrong lug nuts and can cause vibration issues.

Let's look at a tire sized...        read full caption Let's look at a tire sized at P215/60R16-94T. This is an average tire size you might consider for a '67 Mustang. The first number, 215, is the tread width in millimeters. The next number, 60, is called the aspect ratio. Here, sidewall height is expressed as a percentage of tread width. In this case, it's 60 percent, or slightly more than half the width of the tread. The R16 tells you that it's a radial tire made to fit a wheel 16 inches in diameter. Understanding the tire size code will enable you to purchase exactly the right sized tire for your needs.

The federal government requires...        read full caption The federal government requires tire manufacturers to grade tires in three areas. Known as the Uniform Tire Quality Grading System, it provides guidelines for making relative comparisons when purchasing new tires or evaluating tires put on new vehicles. This is helpful, but it is not a guarantee of how a tire will perform or how long it will last because many factors have a significant influence on tire performance and longevity. First, the tread wear grade gives an indication of a tire's relative wear rate. The higher the tread wear number, the longer it should take for the tread to wear down. For example, a tire grade of 400 should wear twice as long as a tire grade of 200. Second is the traction grade, which is an indication of a tire's ability to stop on wet pavement. A higher grade means a shorter stopping distance. Traction is graded from highest to lowest as "AA", "A", "B", and "C". Third are the temperature grades, which are an indication of a tire's resistance to sustained heat From highest to lowest, a tire's resistance to heat is graded as "A," "B," or "C."

Why Nitrogen in Tires?
Craig Knarich of Pit Crew Tire Service explained to us that since nitrogen is denser than oxygen, the larger molecules escape less easily from tires, resulting in a more gradual loss of pressure over time. Research shows that a tire inflated with nitrogen loses its pressure three times slower than if it were inflated with air. As a rough rule of thumb, if your tire pressure is 20 percent below the optimum, you'll reduce tire life by up to 50 percent and the additional rolling resistance can add 10 percent or more to your fuel consumption. Across the life of a tire, that's a big financial penalty. The Department of Energy reports that 4,000,000 gallons of gasoline are unnecessarily wasted every day due to low tire pressure.

Nitrogen is also moisture-free, so pure nitrogen-inflated tires experience less steel-belt and rubber degradation, resulting in longer tire life. The use of nitrogen also reduces valve and wheel corrosion. Nitrogen-inflated tires also run cooler and require less maintenance, according to a Goodyear application bulletin. Non-flammable nitrogen technology has been used in race-car tires for over 30 years.

Decoding Tire Codes
The series of letters and numbers on a tire's sidewall tell a lot about what you're getting for your money as well as the tire's capabilities. The first series of numbers denotes tire size. After that, the two most important things to look for are the service description and the uniform tire-quality grade or UTQG.

Using the information in the service description, we know that a set of our P215/60R16-94T tires will carry a load of 5,908 pounds at up to 118 mph safely. While the load range is fine for our '67 Mustang, the 118 top speed could easily be exceeded, calling for a tire with a higher speed rating. We should note that the speed rating doesn't apply to tires that are worn out, repaired, damaged, retreaded, or not properly inflated.

The second half of the service description is known as the speed rating. Devised to give the buyer an awareness of the tire capability for safe operating speed, it is the T in the 94T service description. Three of the most common speed ratings are S, H, and V. The complete speed-rating table is as follows.

While the first series of...        read full caption While the first series of numbers describe the tire size exactly, the last portion of the code, which is 94T, is known as the service description. It is divided into two parts, the load index and the speed rating. The load index for cars and light trucks ranges from 70 to 110. The load index table is shown below. Capacities listed are for a tire that is properly inflated.

An alignment should be considered...        read full caption An alignment should be considered mandatory on any new wheel and tire purchase. We have seen an improperly aligned car completely ruin a set of new tires within 500 miles. Many tire shops include an alignment with a new tire purchase, so shop around.