215/50 R18 doesn't belong to the most popular dimensions for 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 - 50 is height of the tyre, which is calculated as 50% of the tyre width (215mm), which means the sidewall height has 107.5 mm. The wheel diameter is R18, which means it fits to a 18 inch/457.2mm diameter wheel. The total circumference of the tyre is mm, which is very similar to 245/45 R17
(2049.26 mm), 165/80 R13
(1866.73 mm), 245/60 R18
(2359.96 mm), 175/65 R15
(1911.66 mm), 255/35 R19
(2076.91 mm), 185/50 R16
(1857.94 mm), 255/45 R18
(2157.33 mm).
