365/85 R20 doesn't belong to the most popular dimensions for summer tyres - there are tyre models available, which can be compared to 325/30 R21, 155/60 R15, 155/65 R13. Let's break down the sizing - 85 is height of the tyre, which is calculated as 85% of the tyre width (365mm), which means the sidewall height has 310.25 mm. The wheel diameter is R20, which means it fits to a 20 inch/508mm diameter wheel. The total circumference of the tyre is mm, which is very similar to 235/55 R18(2248.44 mm), 235/65 R18(2396.09 mm), 155/80 R13(1816.47 mm), 245/35 R21(2214.51 mm), 165/65 R13(1711.23 mm), 245/45 R19(2208.85 mm), 175/55 R15(1801.7 mm). There are multiple speed indexes available for summer tyres in 365/85 R20: J(km/h), K(km/h). The same goes for weight indexes: 158, 164.