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 235/60 R17
(2242.47 mm), 155/60 R15
(1781.28 mm), 245/30 R20
(2057.74 mm), 160/60 R17
(1959.73 mm), 245/40 R20
(2211.68 mm), 165/70 R13
(1763.06 mm), 245/50 R20
(2365.62 mm).
