RPM's MPH to gear Ratio/tire size?

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hdfattboy2001

hdfattboy2001

Never Enough Cars!
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Anybody know the conversion to find what my Engine speed at 60MPH with different rear end Ratio's?

Thinking about picking up some 3:73's and dump the 3:23's, but want to know that I can still cruise easily...

I have a 275/60's on the rear end... No Over drive....
 
Just off the top of my head……

A 275-60-15 is 2+" taller than a stock tire. This kills anything those 3.23s were giving you.

The RPMs at 60 will go up a bit with 3.73 but the car should be way better all around.

You could also go with a 275-50-15 that would give you a stock tire height and restore your gear ratio.


With that tall of a tire your effective rear ratio is probably somewhere in the 2s.
 
Thanks guys, for the info..... And yes, those calculators are sweet!
 
cannucky said:
very cool but how do you figure out your tc efficiency ?
Click to expand...

Now that's a crap shoot Cannucky. Is it a loss, medium or tight converter. An old cogger once told me what you do is drive down the highway at 3000 RPM and let off the gas pedal, just a little, and you can feel the converter slippage and see it on the tach. I figure that the one I'm running is about 200-300 RPM therefore 10% therefore medium. I don't know for sure cuss this is my first auto, everything up till now have been 4 speeds.:read2:
 
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