BFGoodrich Trail Terrain T/A 255/55 R20

BFGoodrich Trail Terrain T/A is a winter tyre made in total of 48 sizes, ranging from R15 to R15 - this particular dimension is R20, which means it fits to a 20 inch/508mm diameter wheel. 255/55 R20 is 20mm wider than the narrowest dimension (235) and 30mm narrower than the widest one (285). This tyre profile of 55 means the sidewall height of the tyre is 55% of the tyre width (255mm), which results in 140.25mm sidewall height.