240/40 R18 doesn't belong to the most popular dimensions for summer tyres - there are 5 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 (240mm), which means the sidewall height has 96 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 2039.52 mm, which is very similar to 160/60 R18
(2039.52 mm), 235/30 R20
(2038.89 mm), 275/35 R18
(2041.09 mm), 285/25 R20
(2043.61 mm), 180/60 R17
(2035.12 mm), 215/45 R18
(2044.23 mm), 275/30 R19
(2034.5 mm). There are multiple speed indexes available for summer tyres in 240/40 R18: V
(240km/h). The same goes for weight indexes: 79.
