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Old 08-14-2013, 03:33 PM   #1
Franko
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Will my new Wheels effect speedo?

Hello All,

I went from the 16" OEM with 215/55/16 to the 18" OEM 235/40/18

Will this change my mph or is what shows on my speedo going to still be accurate?


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Old 08-14-2013, 03:39 PM   #2
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.4% slower on your speedo
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Old 08-14-2013, 03:46 PM   #3
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Hey Frank!

Since your tire circumference is virtually the same it shouldn't make any noticeable difference.

215 * .55 = 118.25mm
118.25 * 2 = 236.5mm
16" * 25.4 = 406.4mm

Diameter = 642.9mm
Circumference = Pi * 642.9 = 2018.706mm

Now for the 18" wheels

235* .40 = 94mm
94 * 2 = 188mm
18" * 25.4 = 457.2mm

Diameter = 645.2mm
Circumference = Pi * 645.2 = 2025.928mm

The difference between the two is .356%.

Edit: Forgot to move the decimal.
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Old 08-14-2013, 03:51 PM   #4
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Thanks guys!

And i'd like to publicly thank you once again Bill for the wheels/tires. Were exactly as described.
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Old 08-14-2013, 04:10 PM   #5
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I use this: http://www.rimsntires.com/specs.jsp

It's actually pretty cool when helping decide on wheel sizes
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Old 08-14-2013, 04:29 PM   #6
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Search!!

Here, here, here, and here.

Oh, and also here.
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Old 08-14-2013, 04:30 PM   #7
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No worry! New tire size shouldn't make any noticeable difference
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Old 08-14-2013, 04:42 PM   #8
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Make sure u post pictures of the new wheels!
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Old 08-15-2013, 11:18 AM   #9
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Moved to Wheels & Tires - Sponsored By Tire Rack.
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