Imperial F110 is a summer tyre made in total of 12 sizes, ranging from R20 to R20 - this particular dimension is R22, which means it fits to a 22 inch/558.8mm diameter wheel. 305/40 R22 is 40mm wider than the narrowest dimension (265) and 0mm narrower than the widest one (305). This tyre profile of 40 means the sidewall height of the tyre is 40% of the tyre width (305mm), which results in 122mm sidewall height. In 305/40 R22, there is only one possible speed index for Imperial F110 - "V", which is good for speeds up to 240 km/h.