What Do Tire Numbers Mean?

Are you puzzled by the cryptic numbers and letters on your tires in Moose Jaw? What do tire numbers mean? You’re not alone. Understanding the significance of these markings, such as “What do the numbers on tires mean?” is vital for informed vehicle maintenance decisions. Let Capital Ford Lincoln in Regina be your trusted guide, simplifying this process and demystifying tire markings. Explore tire number meanings with us below!

Tire Number Meaning: What Do Tire Numbers Mean?

So, what do the numbers on tires mean? Understanding the combination of letters and numbers on your tires might feel like cracking a code initially. However, breaking it down systematically reveals valuable information. Let’s explore this using the example of a tire labeled P225/70R16 91S to understand its tire number meaning.

The Letters “P” and “LT”

Most vehicles will have a “P” at the beginning of the tire size: P225/70R16 91S. The “P” stands for “P-metric,” which indicates a “passenger car” tire, according to the Tire and Rim Association. This means the tire is designed for passenger vehicles, including cars, minivans, SUVs, and light-duty pickup trucks.

If you see “LT” instead of “P,” it means “light truck” tires or “LT-metric.” These tires are designed for vehicles that carry heavy cargo or pull trailers.

Similarly, “T” stands for “temporary” (spare tire), and “ST” stands for “special trailer,” which is only used on trailer axles, not drive or steer wheels.

Width

The first number in the tire size is the width, in millimeters, of the tire: P225/70R16 91S. The width is measured from one sidewall to the other. So, a “P225” tire is 225 millimeters wide.

Aspect Ratio

Following the width is the aspect ratio, indicated after the slash: P225/70R16 91S. The aspect ratio is the height of the tire’s sidewall as a percentage of its width. For example, an aspect ratio of 70 means the height is 70% of the tire’s width.

Lower aspect ratio tires, such as a 60 series, typically offer better handling than higher aspect ratio tires, such as a 75 series.

Construction

Next is a letter indicating the tire’s construction: P225/70R16 91S. “R” stands for radial construction, where the internal ply cords are oriented radially (at 90 degrees to the centerline of the tread). Radial tires are the industry standard and are used on most vehicles today.

Other construction types include “D” for diagonal or bias-ply tires, which were common before the 1970s.

Rim Diameter

The number following the construction letter is the rim diameter: P225/70R16 91S. This tire fits a rim with a 16-inch diameter. If you change your rim size, you need new tires that match the new diameter. 

Load Index

The load index indicates how much weight the tire can support when fully inflated: P225/70R16 91S. The number corresponds to a load capacity listed in an index. For example, a load index of 91 means the tire can support a specific weight, as detailed in a load index chart.

Not all tires display the load index, as it’s not legally required. Check your owner’s manual or consult a tire dealer if it’s missing. 

Speed Rating

The final letter is the speed rating: P225/70R16 91S. This letter indicates the maximum speed the tire can handle. For example, “S” is rated for up to 112 mph. Here are common speed ratings and their limits:

• Q: 99 mph
• R: 106 mph
• S: 112 mph
• T: 118 mph
• U: 124 mph
• H: 130 mph
• V: 149 mph
• W: 168 mph
• Y: 186 mph
• ZR: 186+ mph

Higher speed ratings usually mean better handling. Replacement tires should have the same or a higher speed rating to maintain the vehicle’s speed capability.

Severe Snow Conditions

“Tires marked with “M+S” or “M/S” can handle mud and snow conditions. This is common on radial tires.

Choose Capital Ford Lincoln for Your Tire Maintenance!

Now that we’ve answered what do the numbers on tires mean, ensure your vehicle receives top-notch care. Prioritize routine maintenance, such as tire rotations, to optimize performance and longevity. Trust Capital Ford Lincoln in Regina for expert guidance and services tailored to your vehicle’s needs. In conclusion, understanding tire numbers is fundamental to maintaining safety and efficiency on the road, just like oil changes and brake pad replacements. Let Capital Ford Lincoln be your partner in ensuring your vehicle operates at its best.