Apollo Apterra H/T2 is a summer tyre made in total of 3 sizes, ranging from R16 to R16 - this particular dimension is R18, which means it fits to a 18 inch/457.2mm diameter wheel. This tyre profile of 60 means the sidewall height of the tyre is 60% of the tyre width (225mm), which results in 135mm sidewall height. In 225/60 R18, there is only one possible speed index for Apollo Apterra H/T2 - "H", which is good for speeds up to 210 km/h.