195/55 R18 doesn't belong to the most popular dimensions for summer 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 - 55 is height of the tyre, which is calculated as 55% of the tyre width (195mm), which means the sidewall height has 107.25 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 2110.21 mm, which is very similar to 200/60 R17
(2110.52 mm), 215/50 R18
(2111.78 mm), 235/35 R20
(2112.72 mm), 235/40 R19
(2106.75 mm), 325/25 R20
(2106.44 mm), 205/65 R16
(2113.98 mm), 275/30 R20
(2114.29 mm). There are multiple speed indexes available for summer tyres in 195/55 R18: H
(210km/h), V
(240km/h). The same goes for weight indexes: 93.