225/75 R15 doesn't belong to the most popular dimensions for summer 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 - 75 is height of the tyre, which is calculated as 75% of the tyre width (225mm), which means the sidewall height has 168.75 mm. The wheel diameter is R15, which means it fits to a 15 inch/381mm diameter wheel. The total circumference of the tyre is 2257.23 mm, which is very similar to 265/35 R21
(2258.49 mm), 265/30 R22
(2255.04 mm), 235/50 R19
(2254.41 mm), 235/45 R20
(2260.38 mm), 265/40 R20
(2261.95 mm), 235/55 R18
(2248.44 mm), 225/70 R16
(2266.34 mm). There are multiple speed indexes available for summer tyres in 225/75 R15: S
(180km/h), T
(190km/h). The same goes for weight indexes: 102, 106.