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07-02-2015, 01:59 PM
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#1 |
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Registered User
 Join Date: Nov 2014
Location: Gonzales, Louisiana 70737
Posts: 263
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Tire size
I am currenty running 265/75R16 on my 1968 C-20
The speedo reads 50mph, and the GPS says 55mph I am switching to 9.5x16.5 tires to go on my original steelies that I found. According to tire charts, they will be aprox. 1" shorter (30.5 vs 31.5) Is there a way to calculate if this will be closer to correct? And how much this will affect RPM? I have a turbo 400 and 4.10 gears. |
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07-02-2015, 03:02 PM
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#2 |
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Registered User
Join Date: Dec 1999
Location: Austin, TX, USA
Posts: 7,728
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Re: Tire size
1 / 31.5 = 3.18 % So figure it moves your speedo about the same %. So split the differerence.
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07-02-2015, 03:06 PM
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#3 |
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20' Daredevil (Ret)
Join Date: May 2003
Location: Jefferson State
Posts: 13,728
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Re: Tire size
__________________
- Mike - 1972 K20 LWB 350/350/205 RIP El Jay |
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07-02-2015, 03:09 PM
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#4 |
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Registered User
Join Date: Sep 2008
Location: CASA GRANDE AZ
Posts: 4,276
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Re: Tire size
Discount tire has a tire calculator and one of its features is letting you know how much a specific tire will effect the speedometer.
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