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Tire size and speedometer question


SCOTTY

SCOTTY

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Hello out there,

I have a '90 Ranger XLT with 14" stock aluminum wheels.
If I upgrade to 15" wheels, will it affect the accuracy of the speedometer ?

If so, by how many MPH, & would it read faster or slower ?
(I'm thinking slower)

Someone please respond.

Thanks !!
 


ericbphoto

ericbphoto

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My credo
In theory, theory and practice are the same. In practice, they are different.
Wheel diameter has no effect on speedometer. But TIRE diameter does. If you swap to 15" wheels but use tires with the same outer diameter as your original tires, then the speedometer will be correct.

There are charts and calculators in the How To Tech section of this website that will help you figure out what fits and how much speedometer will change. Even articles with pictures of how different sized tires look on various ranges. Click the tab at the top of the page.

Sent from my SM-G960U using Tapatalk
 
SCOTTY

SCOTTY

Active Member
Joined
Dec 26, 2017
Messages
72
Reaction score
121
Points
33
Location
Above the equator
Vehicle Year
1990
Make / Model
Ford Ranger XLT
Engine Size
Cologne 2.9 V6
Transmission
Automatic
2WD / 4WD
2WD
ericbphoto said:
Wheel diameter has no effect on speedometer. But TIRE diameter does. If you swap to 15" wheels but use tires with the same outer diameter as your original tires, then the speedometer will be correct.

There are charts and calculators in the How To Tech section of this website that will help you figure out what fits and how much speedometer will change. Even articles with pictures of how different sized tires look on various ranges. Click the tab at the top of the page.

Sent from my SM-G960U using Tapatalk
Click to expand...
Thanks !
 
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