255/40 R18 - Best tyres 2025 - market overview, tests, reviews

255/40 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 (255mm), which means the sidewall height has 102 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 285/35 R20(2222.68 mm), 225/35 R18(1931.14 mm), 285/45 R21(2481.54 mm), 225/50 R16(1983.6 mm), 295/30 R22(2311.58 mm), 225/60 R16(2124.97 mm), 305/30 R19(2091.04 mm). You can find 255/40 R18 on 14 car models - mainly Mercedes-Benz, BMW, Audi, Ferrari, Jaguar.