When I ordered my CAI + tuner from Lidio at Alternative Auto he mentioned that I would be able to retune my speedo since the tires on my new wheels make the overall diameter about an inch smaller. When I actually installed the tune on my car, the only option I saw about wheels was the "wheel revolutions" parameter or something like that. The options were to increase it or decrease by 500 revolutions per minute I think. Is there where I would be able to retune the speedo to make it correct again? Has anyone else done this, or know anything about it?

The stock size tires were 215/65/16 and my new tires are 245/40/18.

 

its definately not minute because that varys by the speed your moving (obviously) i dont get why they have to make it so complicated. i would call whoever you bought the wheels/tires from and ask how many revolutions per mile the tires or do

 

i just checked out this website http://www.csgnetwork.com/tireinfo4calc.html and according to the site if i'm doing 63mph i'm actually traveling at 60mph, but it feels like when i'm going 70mph i'm actually traveling like 60 or so. This might be because i'm still used to hearing the exhaust i had in my gt before i bought my v6, or maybe something to do with the greater visibility out of the windshield. I guess we'll see when i get my flowmaster this week!

 

good luck. youll love the flows!

 

It's actually revolutions per mile. you want to set your to 785 or as close as possible...

 

do i have to return the tune to stock then go back and retune with the new tire info, or can i just add the revolution per mile info?

 

No need to go back to stock... Just reload Lidio's tune and go into the change parameters...

 

Very good information here. Someone add this to the FAQ!

Switching to 255s soon and this has been very helpful!

 

thanks scrming, i just went for a test drive after resetting to 785, it feels spot on now! i hope all this wasn't in my head, but at least now when the speedometer says 80 it feels like i'm going 80...

 

Cool!