Firestone Firehawk SZ90 245/40 R18

Firestone Firehawk SZ90 is a summer tyre made in total of 41 sizes, ranging from R13 to R13 - this particular dimension is R18, which means it fits to a 18 inch/457.2mm diameter wheel. 245/40 R18 is 50mm wider than the narrowest dimension (195) and 10mm narrower than the widest one (255). This tyre profile of 40 means the sidewall height of the tyre is 40% of the tyre width (245mm), which results in 98mm sidewall height.