Firestone Firehawk Sport is a summer tyre made in total of 33 sizes, ranging from R18 to R18 - this particular dimension is R20, which means it fits to a 20 inch/508mm diameter wheel. 235/35 R20 is 20mm wider than the narrowest dimension (215) and 40mm narrower than the widest one (275). This tyre profile of 35 means the sidewall height of the tyre is 35% of the tyre width (235mm), which results in 82.25mm sidewall height. In 235/35 R20, there is only one possible speed index for Firestone Firehawk Sport - "Y", which is good for speeds up to 300 km/h. In 235/35 R20, Firehawk Sport usually competes against Azenis Fk520, which is a tyre from Falken with a rating of 75%, compared to 70% of the Firestone in question.