When shopping for new tires, you may notice some mysterious letters and numbers printed on the sidewall. These cryptic codes actually contain important information about the tire’s capabilities and ideal use. One common marking you may see is “94w.” But what exactly does this designation mean? Read on for a full explanation of tire sizing, speed ratings, and more.
Demystifying Tire Sizing
The 94w marking refers to two key tire measurements:
- Section width – This is the first part of the code, indicated by the numbers 94. This refers to the width of the tire section in millimeters when properly mounted and inflated.
- Rim diameter – The second part, designated by the “w,” indicates the intended rim diameter in inches. The “w” stands for “wide” and typically means a rim measuring 15 inches.
So a 94w tire is 94 millimeters wide (about 3.7 inches) and intended to fit a 15-inch diameter wheel rim.
Tire sizes follow a standard format of section width/aspect ratio/rim size. Some common examples:
- 215/55R17 – 215mm wide, 55% aspect ratio, 17-inch wheel
- 185/65R15 – 185mm wide, 65% aspect ratio, 15-inch wheel
- 94w – 94mm wide, wide (15-inch) wheel
Matching the tire to the proper rim size is important for safety and performance. Installing a tire on the wrong rim size could lead to tire failure or blowouts.
|Section Width (mm)
|% of Section Width
|Rim Diameter (inches)
The Importance of Speed Ratings
In addition to size, tires are also rated for their maximum safe speed capability. This is known as a speed rating. Common speed ratings include:
- S – 112 mph
- T – 118 mph
- H – 130 mph
- V – 149 mph
- W – 168 mph
Higher speed ratings come at the expense of treadwear – the faster the tire is capable of going, the quicker the tread will wear down.
Speed ratings are established based on specialized track tests under controlled conditions. However, many factors can impact a vehicle’s real world speed capability, including:
- Vehicle condition, age, and maintenance
- Added weight from passengers and cargo
- Road conditions and weather
Exceeding a tire’s speed rating can be dangerous. As speed increases, so do the demands on the tire structure. Heat builds up, grip loosens, and handling is compromised. This increases the chances of blowouts or other failures that could lead to collisions.
For safety, it’s critical to take speed ratings into account when choosing tires. The best practice is to match or exceed the OE manufacturer’s specifications for your particular vehicle. Improper speed ratings put you and your passengers at risk.
All Season vs Summer vs Winter Tires
In addition to size and speed rating, tires are designed for optimal performance in certain weather conditions. The three main categories are:
As the name implies, these tires are made to handle a variety of road conditions – dry, wet, snow, etc. They are the most common type of tire and fit on most passenger vehicles. With their responsive handling and treadwear of 40,000-80,000 miles, all season tires offer a good balance for year-round use.
Summer tires are engineered for maximum dry road grip and high speed handling in warm weather. The tread compound is optimized for lots of contact with dry pavement, but will deteriorate faster in cold temperatures. They also have reduced grooves and siping for displacing water on wet roads. If you live in a warm climate or prioritize sports car performance, summer tires are ideal. Just be aware they lack capability in ice and snow.
Also known as snow tires, winter tires have specialized tread for enhanced traction on snow and ice. They utilize a soft rubber compound designed to maintain flexibility in below freezing conditions. And the tread features aggressive biting edges and numerous sipes for “hooking” into snow. With the improved cold weather grip, winter tires are recommended for drivers in northern climates during the colder months.
Understanding the strengths of each tire type will help narrow your selection. Be sure to consider the climate and road conditions where you live.
Key Takeaways on 94w Tires
- The 94w marking indicates a tire 94mm wide (about 3.7 inches) intended to fit 15-inch rim diameter wheels.
- Speed ratings (S, T, H, V, etc.) are established under controlled track testing and indicate the tire’s maximum safe speed capability.
- Matching or exceeding your vehicle manufacturer’s OE speed rating is crucial for safety.
- Tires are designed for optimal performance in dry, wet, snowy, and icy conditions. Choose the category that fits your climate.
- Exceeding a tire’s speed rating can cause dangerous overheating, loss of traction, and potential blowouts or crashes. Respect the limits.
Still have questions about tire sizing, speed ratings, or finding the ideal tires for your vehicle? Consult a knowledgeable tire retailer or mechanic. With the right tires properly inflated and maintained, you’ll keep your vehicle performing safely for the long haul.
Frequently Asked Questions
What do the numbers and letters on tire sidewalls mean?
The numbers and letters indicate the tire size, speed rating, and other specifications. The first number shows the section width in millimeters. The second number after the slash is the aspect ratio, or profile height as a percentage of width. The letter indicates intended rim diameter. A letter like V or W at the end is the speed rating.
How do I find the right tires for my vehicle?
Check your owner’s manual or existing tires for the OE size, speed rating, and type (all season, summer, etc). Search for replacement tires that match or exceed the OE specifications for your make/model. A tire retailer can also help you identify suitable options.
Can I exceed my tire’s speed rating occasionally?
It’s best not to make a habit of exceeding a tire’s speed rating. For safety, tires should be replaced if driven at high speeds beyond their rating on a regular basis. Moderate, temporary spurts past the limit are less concerning, but sustained high speeds can generate excessive heat that damages the tire.
Do winter tires wear out more quickly in warm weather?
Yes, winter tires will wear out faster in warm weather compared to all season or summer tires. The soft rubber compound that gives winter tires improved cold weather performance also causes the tread to wear more quickly in warm conditions. Limit use of winter tires when temperatures rise.
Should I get the largest width tires that will fit my vehicle?
Not necessarily. Oversized wide tires can sometimes lead to sluggish handling, reduced fuel economy, and additional stress on suspension components. It’s best to stay close to your vehicle’s OE tire width unless you have specific performance needs validated by a mechanic.