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 265/65 R17
(2438.82 mm), 205/55 R15
(1905.38 mm), 275/30 R21
(2194.09 mm), 205/70 R15
(2098.58 mm), 275/40 R21
(2366.88 mm), 215/45 R17
(1964.44 mm), 275/55 R19
(2466.46 mm).
