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 205/65 R16
(2113.98 mm), 275/40 R20
(2287.08 mm), 215/45 R16
(1884.64 mm), 275/55 R17
(2306.87 mm), 215/60 R16
(2087.27 mm), 285/30 R21
(2212.94 mm), 215/75 R16
(2289.91 mm). You can find 255/40 R18 on 14 car models - mainly .
