Bridgestone Potenza Sport is a summer tyre made in total of 132 sizes, ranging from R17 to R17 - this particular dimension is R20, which means it fits to a 20 inch/508mm diameter wheel. 295/30 R20 is 90mm wider than the narrowest dimension (205) and -10mm narrower than the widest one (285). This tyre profile of 30 means the sidewall height of the tyre is 30% of the tyre width (295mm), which results in 88.5mm sidewall height. In 295/30 R20, there is only one possible speed index for Bridgestone Potenza Sport - "Y", which is good for speeds up to 300 km/h.