How does tire size affect speedometer?
08-19-2013, 10:21 AM
#1
Senior Member
Thread Starter
How does tire size affect speedometer?
I just changed my 255/65R17 rims and tires to 275/60R18. Will the affect the speedometer reading? If so, does anyone know how to correct it?
08-19-2013, 10:46 AM
#2
Senior Member
It's going to throw your speedo off by 3.13%(I.e. if your speedo says 65mph you are really going 67.04).
You either need a programmer or have a dealership reprogram to 60/r18. As long as it was a factory offered tire size for the year they can reprogram. If not, they will pick the closest offering.
You either need a programmer or have a dealership reprogram to 60/r18. As long as it was a factory offered tire size for the year they can reprogram. If not, they will pick the closest offering.
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willisod (08-19-2013)
08-19-2013, 11:19 AM
#3
Senior Member
Wdubose ... You either need a programmer or have a dealership reprogram to 60/r18. As long as it was a factory offered tire size for the year they can reprogram. If not, they will pick the closest offering.
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willisod (08-19-2013)
08-19-2013, 11:22 AM
#4
Senior Member
willisod - I just changed my 255/65R17 rims and tires to 275/60R18. Will the affect the speedometer reading?
Tire Size Calculator ««« -click-
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willisod (08-19-2013)
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willisod (08-19-2013)
08-19-2013, 12:29 PM
#6
Senior Member
Thread Starter
Thank you all for the great input. I really appreciate you sharing the knowledge. I had these tires installed at the dealer and never thought to ask about the speedo.
08-19-2013, 03:45 PM
#7
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willisod (08-19-2013)
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08-19-2013, 05:33 PM
#9
Senior Member
most speedometers from the factory usually read faster than you are actually going. check it with a gps, set cruise at at 70 mph and see what the gps is reading. about every time i have put on 1" or bigger tires, my speed was about correct with in 1 mph at 70. just my experience. every vehicle is different. you can do the math yourself using p2.
08-19-2013, 06:08 PM
#10
Senior Member
Thread Starter
most speedometers from the factory usually read faster than you are actually going. check it with a gps, set cruise at at 70 mph and see what the gps is reading. about every time i have put on 1" or bigger tires, my speed was about correct with in 1 mph at 70. just my experience. every vehicle is different. you can do the math yourself using p2.