BF Goodrich g-Grip is a summer tyre made in total of 2 sizes, ranging from R14 to R14 - this particular dimension is R20, which means it fits to a 20 inch/508mm diameter wheel. 255/35 R20 is 80mm wider than the narrowest dimension (175) and -60mm narrower than the widest one (195). This tyre profile of 35 means the sidewall height of the tyre is 35% of the tyre width (255mm), which results in 89.25mm sidewall height. In 255/35 R20, Goodrich g-Grip usually competes against Winterhawk 3, which is a tyre from Firestone with a rating of 0%, compared to 0% of the BF in question.