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Speedo Reads 100mph.

3K views 29 replies 16 participants last post by  DcMoore999 
#1 ·
Sorry. I couldn't figure out where to post this... :shrug:
At 100 on the dash, running 38's, with 3.73's in OD with the TC locked, what RPM was I at and what was my true speed?
:rockwoot:
Thanks guys!
 
#6 ·
I wish I could just go out and do it...
but I also want to know the true speed... and I'm not very good at making the calculator work for me since it's a 1:1 and I suck at math...
Plus i'm on my phone so I still can't do it until tomorrow....Sorry. I couldn't figure out where to post this...
Bren.... Don't be silly... GPS is an expensive speedo. And I can still read maps...
 
#14 ·
Go by a cop, he'll be happy to tell you...
 
#15 ·
Heres a rough estimate:

38/31.8(stock tire height) = 1.20

1.20 is your correction factor so multiply your speed by the correction factor to get your true speed. The mph difference from your speedo and true speed will vary. The faster you go, the larger the difference gets.

As far as RPMs, engine RPMs will be the same regardless of tires.
 
#23 ·
Ha! I can't imagine doing it on bias OR 44 TrXus!!! I actually think those SSR's do a good job of acting like a street tire!
My mom has a stock 6oh and this morning I woke up to her doing 90+ racing some azzhat in a Chevy because he would speed up and slow down so she couldn't pass him in the right lane...
She got PISSED!! I was like...
"If you'd let me tune it...."
LOL LOL

But it felt pretty scary in her truck... It started hopping REALLY bad... I guess she needs shocks huh?
 
#24 ·
I was a little over 130mph on 37's in the orange truck and steadily climbing, then my cps went out. :doh: It gets a little "floaty" on those tires at those speeds.
 
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