215/75 R15 doesn't belong to the most popular dimensions for allround tyres - there are 1 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 (215mm), which means the sidewall height has 161.25 mm. The wheel diameter is R15, which means it fits to a 15 inch/381mm diameter wheel. The total circumference of the tyre is 2210.11 mm, which is very similar to 245/45 R19(2208.85 mm), 245/40 R20(2211.68 mm), 275/40 R19(2207.28 mm), 285/30 R21(2212.94 mm), 225/55 R18(2213.88 mm), 275/45 R18(2213.88 mm), 245/50 R18(2206.03 mm). There are multiple speed indexes available for allround tyres in 215/75 R15: S(180km/h). The same goes for weight indexes: 100.