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Discussion Starter #1
i have 245/50/16's (25.7" tall) on my ponies right now. im thinking of going to 255/45/17 (26.1" tall) on 94 cobras. i know my speedo is off because of my 3.73 gearsbut will going to taller tire make it worse or better? and how much difference?

take care,
adam
 

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Ok I have a tire size calculator just for doin this sort of thing. Here is how fast your speedo says your going and how fast your actually going.
30mph- 30.455mph
60mph- 60.911mph
90mph- 91.367mph
120mph- 121.82mph
150mph- 152.25mph
 

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Here's a quick program that I wrote:
Tire Size Difference Calculator:
http://www.veryuseful.com/mustang/tech/brakes/TireSizeDiff.exe

It'll show you the % diff between 2 tire sizes.

BTW: The reason I wrote the program: For cars with ABS, all 4 tires must be within 3%->5%. So, with the calc, people can see how to go to a wider rear tire and still keep the same overall tire diam.
 

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Discussion Starter #4
thanks a lot guys, (stangPlus2Birds: i cant get the link to work). is that all my car is off???? when i drive 70 on my speedo and have someone follow me they say its closer to 80! i thought it was much more than that.

so with the new tire combo my situation wont be bad at all???

take care,
adam
 

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795.0pacecar said:
Ok I have a tire size calculator just for doin this sort of thing. Here is how fast your speedo says your going and how fast your actually going.
30mph- 30.455mph
60mph- 60.911mph
90mph- 91.367mph
120mph- 121.82mph
150mph- 152.25mph

i don't think that includes the difference caused by 3.73.
 

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Discussion Starter #6
phew, i thought they were more off than that!

take care,
adam
 
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