Ford Mustang Wheel Fitment - One Size Does Not Fit All

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 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 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.