Giti Gar820 is a tyre made in total of 7 sizes, ranging from R18 to R18 - this particular dimension is R18, which means it fits to a 18 inch/457.2mm diameter wheel. 215/75 R17.5 is 10mm wider than the narrowest dimension (205) and 30mm narrower than the widest one (245). This tyre profile of 75 means the sidewall height of the tyre is 75% of the tyre width (215mm), which results in 161.25mm sidewall height. In 215/75 R17.5, there is only one possible speed index for Giti Gar820 - "", which is good for speeds up to km/h.