You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!
Go by the rear tire size to calibrate the speedo on a staggered setup.
Ever do a burnout? Your car isn't moving, except for your back tires, yet the speedo will show a mph (thats why everyone tells you to do your burnout at around 55mph in 2nd gear).
This ad is not displayed to registered or logged-in members. Register your free account today and become a member on Mustang Forums!
__________________
05 Redfire GT: WHIPPLE HO @ 10psi, VMP dyno tune & other goodies - stock block, stock exhaust, stock 3.55s 11.324 @ 121.84 w/ 1.627 http://www.youtube.com/watch?v=dlBxdF5IqFM
11.36 @ 122.72 w/ 1.663 http://www.youtube.com/watch?v=BoGf6DiMVk4
Previous runs:
CAI+tune only 12.877 @ 106.79 w/ 1.819
CAI+tune+suspension 12.783 @ 108.05 w/ 1.841
both on stock tires
Please do not link companies in your sig
"Actually, such a force doesn't exist. Try reading a physics manual next time."
Hey Will Hunting, maybe you can tone it down a bit. A common mistake and really not a big deal. You have a very well writen definition of, "centrifugal force", but your delivery needs a little work Jr. Remember it's the internet no one cares how big you think your IQ is.
Just my 2 cents on what I thought was an unneccessay comment, not starting any battles.
Why would it be such a drastic difference from the manufacturer's site?
Because wrapping a tape measure around the tire and dividing that into the measured mile is NOT the correct way to calculate the tire revs per mile. A tire's contact patch will throw off the calculation, so you have to use the manufacturer's published number. If the tire company doesn't publish a number for your particular tire, then you are better off using the number from a different company for the same size tire (not the best choice, but better than guessing).
Using 157db's method will result in your speedo being off. But here's the question - If the correct number is 770, but you plug in 740 into your handheld tuner, will be speedo be reading faster or slower than you are actually traveling? I know the answer, but I just wanted to give you something to think about this morning.
__________________ 1985 SSP Mustang - California Highway Patrol Unit #E408395
We are the music makers, and we are the dreamers of dreams - Willie Wonka
Because wrapping a tape measure around the tire and dividing that into the measured mile is NOT the correct way to calculate the tire revs per mile. A tire's contact patch will throw off the calculation, so you have to use the manufacturer's published number. If the tire company doesn't publish a number for your particular tire, then you are better off using the number from a different company for the same size tire (not the best choice, but better than guessing).
Using 157db's method will result in your speedo being off. But here's the question - If the correct number is 770, but you plug in 740 into your handheld tuner, will be speedo be reading faster or slower than you are actually traveling? I know the answer, but I just wanted to give you something to think about this morning.
That kind of thinking makes my head hurt and I even took physics in college but that was a LONG time ago I completely agree with using the manufacturer's web site as a reference when changing the revs/mile with a tuner. FWIW, I recently switched from Nitto 555 295/45/18 to Toyo Proxes ST II of the same size, and the revs/mile each manufacturer listed on their web site was different (only by 1 rev/mile, but I want the speedo to read as accurate as possible), so I adjusted accordingly with my Predator
__________________
Dave
2005 Mineral Gray Mustang GT: Plain, clean and simple. Wrapped up nice and tight.
OK, then measure out 63360 inches on a straight road
and drive from zero inches to 63360 inches and count
the amount of times the tire rotates 360 degrees.
Do this at 20MPH, 30MPH, 40MPH, 50MPH, 60MPH,
70MPH, 80MPH, 90MPH, 100MPH and finally 110MPH.
Add up the totals and average them.
Hows that for a way to get the revs/mile exactly for
any particular tire at any particular load and air pressure.
Jesss, split a few hairs next time....
What me give useful info? Never.
Just here to bug the crap out of everyone.
__________________
NON PUMKIN JACKER
Quote:
Originally Posted by Boozshey
Oh yeah, I forgot Norm was God on here.
Give me a break!!!
Quote:
Originally Posted by Norm Peterson
<rises to the bait>
. . . Definitely not God.
Norm
This forum is owned and operated by Internet Brands, Inc., a Delaware corporation. It is not authorized or endorsed by the Ford Motor Company and is not affiliated with the Ford Motor Company or its related companies in any way. Ford® is a registered trademark of the Ford Motor Company
I completely agree with using the manufacturer's web site as a reference when changing the revs/mile with a tuner. FWIW, I recently switched from Nitto 555 295/45/18 to Toyo Proxes ST II of the same size, and the revs/mile each manufacturer listed on their web site was different (only by 1 rev/mile, but I want the speedo to read as accurate as possible), so I adjusted accordingly with my Predator 
