Determining Tire Size: Understanding Numbers, Indexes & DOT – With Comparison Chart
Determining tire size: Easily read 205/55 R16 & Co., understand index & DOT, and compare with a table. This is how you safely order suitable tires online.
Determining Tire Size: Understanding Numbers, Index & DOT – With Comparison Table
Determining tire size is the most important step before ordering tires online. Most incorrect purchases are not due to "poor advice," but because width, aspect ratio, rim size, or index were read incorrectly. In this article, you will learn to safely determine tire size in just a few minutes: What does 205/55 R16 mean? What do the load and speed indexes indicate? And how do you use DOT/age effectively?
How to read a typical tire specification
Example: 205/60 R16 92H
- 205 = Tire width in mm
- 60 = Aspect ratio (height in relation to width)
- R = Radial construction
- 16 = Rim diameter in inches
- 92 = Load index (carrying capacity)
- H = Speed index
If you want to delve deeper: Here, tire marking (including index and DOT) is explained very clearly: Tire Marking Explained. For the speed index, there is an additional dedicated explanation: Understanding Speed Index.
Where to find the correct size
- In your registration certificate (vehicle registration document)
- On the sidewall of the currently mounted tires
- Sometimes in the door frame/fuel filler flap (often pressure values)
Why Load Index & Speed Index are Important
Many only look at "205/55 R16." That's not enough. Load index and speed index are safety and regulatory data. Especially for road trips, family cars, or vans, the load capacity is crucial. Tip: If you are unsure, stick to the vehicle's specifications and do not choose "just any index."
DOT and Tire Age: Briefly Explained
You read the production date via DOT (usually the last 4 digits: week/year). If you buy used tires, DOT is a must. A very clear explanation on this: Reading Tire Age and DOT Correctly.
Comparison Table: What you should check before buying
| Criterion | Example | What it's about |
|---|---|---|
| Size | 205/60 R16 | Must fit rim & vehicle |
| Load Index | 92 | Load capacity per tire |
| Speed Index | H | Permissible maximum speed |
| Season | Summer/Winter/All-season | Grip per weather/temperature |
| DOT | 1024 | Week/year of production |
How to find suitable tires in the shop (without detours)
Once you have finished determining tire size, the selection becomes much easier. You can start broadly with Tires or directly check new models via New Tires. Seasonal direct entries: Summer Tires – New and Winter Tires – New.
For common sizes, you can also use size-specific collections, e.g., Summer Tires 205/60 R16 or Winter Tires 205/65 R16.
Common mistakes when determining tire size
- Misunderstanding aspect ratio: "55" is not the rim, but the aspect ratio.
- Ignoring the index: Size fits, index doesn't – that's a problem.
- Forgetting DOT: especially important for used tires.
Conclusion: Determine tire size and then order safely online
Determining tire size is the basis for a stress-free tire purchase. If size, index, and DOT match, you can quickly and safely compare online. Start now with Tires or filter directly by season. If you correctly determine tire size, you save time, returns, and uncertainty – and order the right tires on the first try.