Understanding Tyre Sizes: What Do Those Numbers Mean?
Those confusing numbers on your tyre sidewall actually contain vital information about your tyre's size, capabilities, and safety ratings. Understanding them helps you make informed purchasing decisions and ensures you buy the right tyres for your vehicle.
The Standard Format: 225/45R17 91V
Let's break down a typical tyre size marking using the example 225/45R17 91V:
Width (millimeters)
The tyre's width from sidewall to sidewall. This is 225mm wide. Wider tyres provide more grip but can reduce fuel efficiency.
Aspect Ratio (profile)
The height of the sidewall as a percentage of the width. Here, the sidewall height is 45% of 225mm = 101mm. Lower numbers mean a shorter, sportier sidewall.
Construction Type
R = Radial (99% of modern tyres). Other types include D (Diagonal/Bias) and B (Belted), but these are rare.
Rim Diameter (inches)
The wheel size this tyre fits. This tyre requires 17-inch wheels. Common sizes in Dubai: 14" to 22".
Load Index
Maximum weight each tyre can carry. 91 = 615 kg per tyre. Never go below your vehicle's recommended load index!
Speed Rating
Maximum safe speed. V = 240 km/h. Important for Dubai highway driving. Never go below your vehicle's rating!
Speed Rating Chart
| Rating | Max Speed | Typical Use |
|---|---|---|
| S | 180 km/h | Family sedans |
| T | 190 km/h | Economy cars |
| H | 210 km/h | Mid-range sedans |
| V | 240 km/h | Sports sedans |
| W | 270 km/h | High-performance cars |
| Y | 300 km/h | Supercars |
Load Index Reference
| Index | Max Load (kg) | Index | Max Load (kg) |
|---|---|---|---|
| 85 | 515 kg | 95 | 690 kg |
| 87 | 545 kg | 100 | 800 kg |
| 91 | 615 kg | 105 | 925 kg |
Other Important Markings
DOT Code
Manufacturing date. Example: DOT ... 2521
= Week 25 of 2021
M+S Marking
Mud and Snow rated. Suitable for light winter conditions.
XL / RF
Extra Load / Reinforced. Higher load capacity for heavier vehicles.
Run Flat (RFT)
Can drive short distances without air. Common on BMW.
Important: Never Guess Your Size!
Installing the wrong tyre size can affect speedometer accuracy, handling, braking distances, and even void your insurance. Always match your vehicle manufacturer's specifications.
Not sure what size you need? Our experts can tell you instantly. Call +971 50 740 5423 or use our online tyre finder.
Popular Sizes in Dubai
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