255/40 R18 doesn't belong to the most popular dimensions for allround tyres - there are 0 tyre models available, which can be compared to
155/60 R15,
170/60 R17,
160/60 R14. 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 2077.22 mm, which is very similar to 255/35 R19
(2076.91 mm), 255/45 R17
(2077.54 mm), 255/30 R20
(2076.59 mm), 215/65 R15
(2075.02 mm), 305/25 R20
(2075.02 mm), 195/65 R16
(2073.14 mm), 225/40 R19
(2081.62 mm). There are multiple speed indexes available for allround tyres in 255/40 R18: V
(240km/h), W
(270km/h), Y
(300km/h). The same goes for weight indexes: 99. You can find 255/40 R18 on 14 car models - mainly .