245/75 R17 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 (245mm), which means the sidewall height has 183.75 mm. The wheel diameter is R17, which means it fits to a 17 inch/431.8mm diameter wheel. The total circumference of the tyre is 2511.08 mm, which is very similar to 285/60 R18(2510.76 mm), 265/65 R18(2518.61 mm), 285/65 R17(2520.5 mm), 265/70 R17(2522.07 mm), 265/75 R16(2525.53 mm), 285/50 R20(2491.28 mm), 235/85 R16(2531.81 mm). There are multiple speed indexes available for summer tyres in 245/75 R17: Q(160km/h), S(180km/h), T(190km/h). The same goes for weight indexes: 112, 121.