Bridgestone Alenza 001 is a summer tyre made in total of 57 sizes, ranging from R17 to R17 - this particular dimension is R18, which means it fits to a 18 inch/457.2mm diameter wheel. 225/60 R18 is 10mm wider than the narrowest dimension (215) and 50mm narrower than the widest one (275). 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 are 2 possible speed indexes for Bridgestone Alenza 001 - "H","W", which are good for speeds up to 210, 270 km/h.