Understanding Tire Service Descriptions: Speed Rating and Load Index

There never seems to be a shortage of questions you are asked when you inquire about tires. What size do you need? What speed rating do you require? How will you be using them? What load index do you need?

Where do you find this information, and what does it even mean? It may seem overwhelming, but knowing a few key pieces of information will help you find the correct tire for your vehicle.

Where to find Load Index and Speed Rating on your tire

On the sidewall of your tire, your tire size is indicated in the format of 215/60R16. Immediately following the tire size is another number and a letter like 94S. This is the load index and speed rating of your tire. Let’s decipher it.

Load Index

The number is the load index. It indicates how much weight the tire can bear. The higher the load index number, the more weight it can carry:

Example Load Index Chart

As you can see, the number 94 means each tire can bear up to 1,477 lbs of weight, or 670 kg. The load index of your tires shouldn’t be reduced. A tire is matched precisely to a vehicle when it is engineered. Using a tire with a lower load index could result in undesirable tire wear or failure. You may choose to use a load index higher than your vehicle was originally equipped with, and the load capacity will increase.

Speed Rating

Beside the load index is a letter which indicates the speed rating. In our example the letter is S. As with the load index, the higher the letter in the alphabet, the higher the speed rating:

Example Speed Rating Chart

The speed rating is the maximum speed a tire can be operated up to. A tire’s speed rating is void if it has been punctured, patched, or otherwise damaged. The manufacturer can no longer guarantee the safe operation of the tire at high speed.

High Performance Speed Rating

High performance tires have a speed rating in a slightly different fashion. In the tire size, the addition of a Z indicates it is a tire capable of speeds in excess of 149 mph. It is shown as: 215/60ZR16

That was thought to be as much rating as was needed, and the Z rating encompassed all tires rated at 149 mph and higher. Since the inception of Z-rated tires, further clarification has occurred that identified specific speed ratings for above-149 mph speeds. W-rated tires indicate a tire capable of speeds up to 168 mph, and Y rated tires up to 186 mph. Anything beyond Y rated tires is shown with the load index/speed rating in parentheses. For example, it could be shown as (99Y).


The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

Related articles

Are Wider Tires Better?
The The size and width of the tires on your vehicle determines how your vehicle will handle in different conditions. There are several factors that go into the decision of which tires to equip your vehicle with, including: The...
How Do I Take Care of My New Tires?
You’ve You’ve equipped your car with a brand new set of tires, replacing the old set of worn out rubber. They were noisy, and every time you had to brake hard, you were losing traction. Now you’ve spent your hard-earned...
How Do I Take Care of My New Tires?
You’ve You’ve equipped your car with a brand new set of tires, replacing the old set of worn out rubber. They were noisy, and every time you had to brake hard, you were losing traction. Now you’ve spent your hard-earned...

Related questions

Flapping noise after I accelerated in low gear

Hello - your symptoms suggest a tire that is separating. IF the tread starts to separate from the structural "belts" - fiber or steel mesh - a tire will make the noises you describe. It also means the tire will...

Flapping sounds at average speed, steering wheel shakes

This type of situation is caused by a rotational imbalance or load variation on the tires. My recommendation would be to have the tire road force balanced and matched for least vibration. This type of balance will put the...

When driving it feel like the tires are wobbling, but they are not.

You should not drive the vehicle until having the wheels checked to make sure they are seated correctly and secured tightly. If the rims are seated and tight then you may have a bad tire that have broken internal steel...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1 (855) 347-2779 · hi@yourmechanic.com