Benefits of replacing 245 70 16 with 245 75 16?

Answer 1

That middle number, the 70 or 75, is the 'aspect ratio', its the ratio of tire height to tire width (height rim to road, not overall diameter). The first number (the 245) is the actual width, in mm. So with the same width, the higher apsect ratio tire (the 75) is going to be taller. The 75's height would be 75% of the width, 75% of 245, or 184. So 184mm x 2 (for the other end of the tire), + 16" (~40mm), is the total tire diameter (about 408mm). The 70 is only 70% of 245 (about 382mm diameter). If you're going for sporty, look & handling, you usually want a lower apsect ratio. If you want more meat between rim and road, you want a higher apsect ratio. So if you're worried about pothole damage, or want a cushier ride, you generally want a higher apsect ratio. The taller tire is also going to mean taller overall gearing, so at the same engine speed, it'll be like you're in a slightly higher gear. That means less acelleration, but better fuel mileage. Also less engine revs on the highway (for a given speed), so a little less engine wear per mile. But 70 is still pretty high, you've got plenty of meat for decent ride, rim protection, etc. So the question is, with the 75's, did you feel the ride or rim protection was lacking, or the highway revs could have been less and you'd still have had enough throttle response? That should tell you if you'd be happier with a higher apsect ratio tire.