225/50 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 (225mm), which means the sidewall height has 112.5 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 R18
(2129.06 mm), 170/60 R17
(1997.42 mm), 245/65 R17
(2357.14 mm), 175/70 R13
(1807.04 mm), 255/35 R20
(2156.7 mm), 185/55 R14
(1756.46 mm), 255/45 R19
(2237.13 mm).
