395/85 R20 doesn't belong to the most popular dimensions for allround 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 (395mm), which means the sidewall height has 335.75 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 225/60 R15(2045.18 mm), 295/45 R20(2430.02 mm), 225/75 R16(2337.03 mm), 325/30 R21(2288.34 mm), 235/45 R18(2100.78 mm), 235/55 R19(2328.23 mm), 235/70 R16(2310.33 mm). There are multiple speed indexes available for allround tyres in 395/85 R20: G(km/h), K(km/h). The same goes for weight indexes: 168.