Bridgestone R168 is a tyre made in total of 8 sizes, ranging from R17 to R17 - this particular dimension is R20, which means it fits to a 20 inch/508mm diameter wheel. 245/70 R19.5 is 235mm wider than the narrowest dimension (10) and 140mm narrower than the widest one (385). This tyre profile of 70 means the sidewall height of the tyre is 70% of the tyre width (245mm), which results in 171.5mm sidewall height. In 245/70 R19.5, there is only one possible speed index for Bridgestone R168 - "", which is good for speeds up to km/h.