265 is the tyre width in millimetres, 40 is the sidewall height as a percentage of the width (a lower-profile design), and R18 means it fits an 18 inch wheel. You still need to match the load index and speed rating printed on your current tyre or listed in your vehicle handbook.
Choose the same load index and speed rating as specified on the tyre placard (often in the door shut) or in the handbook, and do not go below the vehicle requirement. Many 265/40 R18 fitments are performance-focused, so the correct speed rating is especially important for stability and insurance compliance.
Some vehicles require XL (extra load, sometimes marked Reinforced) in this size, especially where it is used on the rear axle or on heavier, high-torque cars. Check your existing sidewall markings and your manufacturer specification, then select XL only if it matches the required load rating for your car.
Summer tyres suit temperatures consistently above 7C and give the sharpest handling feel for this wide, low-profile size. Winter tyres are the safer choice when temperatures regularly drop below 7C, improving braking and traction in cold, wet conditions. All-season tyres balance both for year-round UK use if you prefer one set, but confirm availability in 265/40 R18 for your preferred brand.
It depends on your car and wheel width. The tyre is 10 mm wider and may reduce clearance to suspension components or wheel arches, and it can change the rolling circumference enough to affect speedometer accuracy. Check the approved sizes for your exact model and confirm your wheel width is compatible, then inform your insurer if you make a size change.
