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Need to know when changing car tires! How to read tire sidewall symbols and choose car tires

Jul 3 , 2026 อ่านแล้ว 3,596 ครั้ง

How to read car tire sidewall numbers and choose the right tires for your car, Newbie Edition, Updated 2026

Have you ever been confused when it's time to change car tires and you look at the numbers on the sidewall, wondering what "265/60R18 114H" means? This article will help you understand the basic codes on car tire sidewalls in 5 minutes and confidently choose your own tires.

How to Read Car Tire Sidewall Symbols

Position in image	Example from image	Technical Name	Meaning
Width	265	Section Width	Tire tread width in millimeters (mm)
Aspect Ratio	60	Aspect Ratio	Ratio of sidewall height to tread width, in % (e.g., 60% of 265 mm)
Radial	R	Radial Construction	Radial tire structure, which is standard for general automobiles
Rim	18	Rim Diameter	Rim size that the tire supports, in inches (must match the wheel size exactly)
Load Index	114	Load Index	Maximum load index per tire (requires consulting a conversion chart to kilograms)
Speed Index	H	Speed Rating	Symbol for the maximum speed the tire can support

What is Aspect Ratio?

It is the ratio of sidewall height to tread width. The smaller the number, the lower the sidewall. The larger the number, the higher the sidewall. This directly affects the driving feel.

Aspect Ratio	Sidewall Characteristic	Steering Response	Comfort	Suitable for car/use
30-45 (Low)	Very low, thin sidewall	Precise, good cornering	Stiff, feels every bump	Sports cars, racing cars, large wheels for aesthetics
50-55 (Medium)	Medium sidewall	Balanced precision and comfort	Medium	General sedans, Eco Cars
60-65 (High) From Cover image	High, thick sidewall	Soft, good shock absorption	Very comfortable, absorbs potholes well	Small to medium cars, SUVs, pickup trucks
70 and above (Very high)	Very high sidewall	Very soft, but sways in corners	Most comfortable	Light trucks, off-road vehicles

The cover image uses an aspect ratio of 60 with 18-inch rims because this proportion is popular among new SUVs and pickup trucks. You should not change the tire's aspect ratio too much from the original, as it will affect the overall tire diameter, causing the speed displayed on the speedometer to deviate from the actual speed and potentially impacting ABS or ESC braking systems.

What is 'R' Radial Tire?

It refers to the method of weaving the internal tire carcass cords. Almost all tires used in current vehicles have a radial structure. An older type was the Bias-Ply structure (diagonal canvas tires), which is now rarely used in passenger cars.

Feature	Radial Tire	Bias-Ply Tire (Diagonal Structure)
Carcass cords	Laid perpendicular to the direction of rotation	Laid diagonally overlapping in layers
Contact patch	Consistent throughout driving	Narrower and easily changes shape at high speeds
Heat accumulation	Better heat dissipation	High heat accumulation
Lifespan	Longer	Wears out faster
Fuel consumption	More economical	Less economical
Usage	Standard for almost all car models	Found sometimes in trailers or some older car models

Speed Rating Chart Every Newbie Should Know

The numbers refer to the ETRTO (European Tyre and Rim Technical Organisation) standard, which is a common standard used by tire manufacturers worldwide.

Symbol	Max Speed (km/h)	Suitable for car type
S	180	Family car, Eco Car
T	190	General sedan, Family SUV
H (from Cover image)	210	SUV, Premium pickup truck
V	240	High-performance car, some EV models
W	270	Sports car, High-performance EV
Y	300	Supercar, Premium sports car

Note: Choosing a Speed Rating does not mean you need to drive at that actual speed, but rather it indicates the tire's structure and its differing heat resistance. The higher the Rating, the stronger the tire structure and the better the car's handling.

Most Common Load Index Chart

The numbers refer to the ETRTO (European Tyre and Rim Technical Organisation) standard, which is a common standard used by tire manufacturers worldwide.

Load Index	Max Load (kg/tire)
91	615
94	670
97	730
100	800
106	950
110	1,060
114 (from Cover image)	1,180
118	1,320

Recommendation: You should not choose tires with a Load Index lower than the value specified in your car's manual, as this can cause the tire to overheat and burst while driving.

Other Symbols on Car Tires

Tire Manufacturing Date

The last 4 digits of the code, e.g., "1125," mean manufactured in the 11th week of 2025 (approximately mid-to-late March 2025).
You should buy tires manufactured no more than 1-2 years ago, as tires have a shelf life even when not in use.
Tires stored for more than 6-7 years should be replaced, even if they still have tread, because the rubber deteriorates.

American Standard Used by Many Tire Brands: Treadwear / Traction / Temperature

UTQG Rating Value	Meaning
Treadwear	A number indicating the durability of the tire tread. Higher numbers mean longer lasting (but often less grip than lower numbers).
Traction (AA, A, B, C)	Ability to grip on wet roads. AA indicates best grip.
Temperature (A, B, C)	Resistance to heat accumulation while driving at high speeds. A indicates best heat resistance.

Checklist Before Changing New Tires

Check the original tire size from the sticker on the driver's side door frame or the car manual.
Load Index must not be lower; it must be the same or higher.
Speed Rating must not be lower; it must be the same or higher.
Check the tire manufacturing date *very important*. You should buy tires manufactured no more than 1-2 years ago.
Do not only look at cheap prices; choose the tire type suitable for your use.
Do not change tires one by one.

Summary

Reading tire sidewall symbols is a basic skill everyone should have for safety and to save money from choosing the wrong tire specifications. If you want to see various car and tire models up close, come meet us at the Motor Expo from December 2-13, 2026.