Brakes and Tires
Ford Aspire
Ford Ranger XLT

You bought a used 97 aspire with P17570R13 tires on it you understand the recommended tire size is P165R7013 approximately how much faster will your speedometer be reading?



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there will be a slight difference. it's only 10 millimeters wider. you can't really tell


The aspect ratio (in this case it is 70) means that the rim to tread height is 70% of the width.

70% X 165mm = 115.5mm (recommended)

70% X 175mm = 122.5mm (installed)

That means that the tire radius increases from (190.5mm* + 115.5mm =) 306mm recommended to 190.5mm + 122.5 mm) = 313mm.

*Note: 190.5mm is half your 13" rim diameter in millimeters.

Your tire will roll 1.02 times further for the same speedometer reading. If you are reading 50 miles per hour, your actual speed would be 50 mph X 1.02 = 51.1 mph.

You might not want to push speed limits as much as you might be used to.