235/35 R18 doesn't belong to the most popular dimensions for summer tyres - there are 1 tyre models available, which can be compared to 155/60 R15, 170/60 R17, 160/60 R14. Let's break down the sizing - 35 is height of the tyre, which is calculated as 35% of the tyre width (235mm), which means the sidewall height has 82.25 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 1953.13 mm, which is very similar to 190/50 R17(1953.44 mm), 185/65 R15(1952.5 mm), 205/40 R18(1951.56 mm), 195/55 R16(1950.61 mm), 235/40 R17(1947.16 mm), 160/60 R17(1959.73 mm), 215/45 R17(1964.44 mm). There are multiple speed indexes available for summer tyres in 235/35 R18: Y(300km/h). The same goes for weight indexes: 86.