255/40 R18 tyres are available at the Rīgas Riepas online store, with prices starting from 57,00 €. In this size you will find summer, winter and all-season tyres from leading brands, including Michelin, Pirelli, Continental and others.
How to read tyre sizes and what they mean
Tyre size markings may look complicated, but they are actually easy to understand. The correct tyre size is critical for safe and economical driving - unsuitable tyres can affect speedometer readings, the operation of the ABS and ESP systems, and the car's handling.
Decoding the tyre size marking
Let's take the example 255/40 R18 99Y:
- 255 - tyre width in millimetres. Wider tyres provide better grip but increase fuel consumption and the risk of aquaplaning.
- 40 - profile height as a percentage of the width. In this case the profile height is 40% of 255 mm, which is roughly 102 mm. A lower profile improves handling but reduces comfort.
- R - radial construction. Virtually all modern passenger car tyres are radial.
- 18 - rim diameter in inches. It must match your car's rims.
- 99 - load index. Indicates the maximum load per tyre (99 = 775 kg).
- Y - speed rating. Indicates the maximum permitted speed (Y = 300 km/h).
Load index table
The load index indicates the maximum weight a tyre can carry at the correct pressure. The most common indexes for passenger cars:
- 75 - 387 kg, 80 - 450 kg, 85 - 515 kg
- 88 - 560 kg, 91 - 615 kg, 94 - 670 kg
- 97 - 730 kg, 100 - 800 kg, 104 - 900 kg
SUVs and off-road vehicles usually require a higher load index. Never use tyres with a lower load index than the manufacturer recommends.
What the speed rating means
The speed rating indicates the maximum speed at which a tyre can operate safely. The most common ratings:
- T - 190 km/h, H - 210 km/h, V - 240 km/h
- W - 270 km/h, Y - 300 km/h, Z - over 240 km/h
For winter tyres it is acceptable to use a speed rating one grade lower than for summer tyres, but never lower than Q (160 km/h).
How to find the right size for your car
The tyre size is stated in several places: on the sidewall of your current tyres, on a sticker in the door frame or on the fuel filler cap, and in the owner's manual. Some cars allow several tyre sizes - in that case, follow the manufacturer's recommendations, taking your driving conditions and priorities into account. A step-by-step walkthrough with examples is available in the article how to find your tyre size.
The most popular tyre sizes in Latvia
The most frequently requested tyre sizes in Latvia are 205/55 R16, 195/65 R15 and 225/45 R17 - they fit the most popular car models, such as the VW Golf, Škoda Octavia and Toyota Corolla. In the SUV segment, the 235/55 R18 and 215/65 R16 sizes dominate. Use our search to quickly find tyres that fit your car exactly.
Additional markings on tyres
Besides the basic size, tyres may carry other important markings: XL or Extra Load - reinforced construction for heavier loads; M+S - suitable for mud and snow; 3PMSF (three-peak mountain snowflake symbol) - meets winter tyre testing standards; DOT - date of manufacture (for example, DOT 2024 means week 20 of 2024). Tyres older than 5-6 years can lose their elasticity regardless of tread depth.