205/40 R18 - Best tyres 2025 - market overview, tests, reviews

205/40 R18 doesn't belong to the most popular dimensions for tyres - there are tyre models available, which can be compared to 325/30 R21, 155/60 R15, 155/65 R13. Let's break down the sizing - 40 is height of the tyre, which is calculated as 40% of the tyre width (205mm), which means the sidewall height has 82 mm. The wheel diameter is R18, which means it fits to a 18 inch/457.2mm diameter wheel. The total circumference of the tyre is mm, which is very similar to 255/40 R17(1997.42 mm), 185/55 R15(1836.26 mm), 255/45 R20(2316.92 mm), 185/75 R14(1988.94 mm), 255/65 R16(2318.18 mm), 195/50 R15(1809.56 mm), 265/30 R22(2255.04 mm).