I went from a tire size P235/70R17 to a LT265/70R17. The P235 has a diameter of 29.9 and the 265 is 31.6. ( I think that's correct) How many miles will it have actually gone when the odometer shows 100 miles? What difference will it be in MPH on my speedometer? Is there a online chart that will tell me?
2007-02-07 09:08:40 · 3 answers · asked by sammye 1 in Cars & Transportation ➔ Other - Cars & Transportation
Mesafuzzy has the math down to a science. However, to clarify a point: larger diameter tires result in the speedometer under reading actual speed. So using the 5.3% correction factor: indicated 60mph is actually 63.2mph. Note two things: 1) the speedometer counts tire rpms to indicate speed (usually indirectly). 2) Since the speedometer's original calibration is based upon tire circumference of 29.9", a circumference change to 31.6" will result in more distance traveled per tire revolution.
2007-02-07 13:02:00 · answer #1 · answered by db79300 4 · 0⤊ 0⤋
Lets see.....
5280 feet = 1 mile
29.9" tire = 93.93" around = 674.5 revolutions per mile
31.6" tire = 99.27" around = 638.3 revolutions per mile
5.3% difference, 100 miles = 94.7 miles.
Speedometer error will be the same 5.3%
60 MPH = 56.8 MPH
2007-02-07 17:30:20 · answer #2 · answered by Anonymous · 1⤊ 0⤋
Had the same question myself recently......discount tire has a chart on their website with that info....or it might just be easier to give them a ring on the phone and let them look it up for you...:)
2007-02-07 17:13:19 · answer #3 · answered by Justin D 1 · 0⤊ 0⤋