275/50 R21 doesn't belong to the most popular dimensions for winter tyres - there are 2 tyre models available, which can be compared to
155/60 R15,
170/60 R17,
160/60 R14. Let's break down the sizing - 50 is height of the tyre, which is calculated as 50% of the tyre width (275mm), which means the sidewall height has 137.5 mm. The wheel diameter is R21, which means it fits to a 21 inch/533.4mm diameter wheel. The total circumference of the tyre is 2539.66 mm, which is very similar to 235/85 R16
(2531.81 mm), 265/75 R16
(2525.53 mm), 265/70 R17
(2522.07 mm), 255/70 R18
(2557.88 mm), 285/65 R17
(2520.5 mm), 275/65 R18
(2559.46 mm), 265/65 R18
(2518.61 mm). There are multiple speed indexes available for winter tyres in 275/50 R21: R
(170km/h), T
(190km/h), V
(240km/h), W
(270km/h). The same goes for weight indexes: 113.
