The change of sizes is determined a formula which changes tire to 5% lower profile with 10 mm wider cross section. This implies that the reducing aspect ratio is 5. Now, adding 10 to 195 makes it 205 but subtracting 5 from 75 making it 70. By changing the tire size of 195/75 R15 using the this formula, this will be changed to size of 205/70 R15. Therefore, the right option is 205/70 R15.
