[mcqueen]

Got my SCT SF3 tuner today and I love it (even though I'm only running an 87 oct economy tune right now, it's noticeably better than stock). I was going to change the wheel size with the tuner but I started scrolling through the list and it was measured in revs/mile and I'm not sure what that would be for either 17 or 18 inch wheels. Any idea what I should set the revs/mile at for both of those? (I'll be swapping from 17 to 18 inch wheels in a few weeks).

Also I took the chance to check my CEL codes and I got the usual O2 sensor code but then I found the P1000 which is OBDII Monitor Testing Incomplete. I've got no idea what that even means or how to fix it. Can someone enlighten me?

[WhtStang00]

for revs per mile, try this -

Tire Size Calculator - tire & wheel plus sizing

[mcqueen]

Cool thanks! Any idea what stock tire size is on a 2000 Mustang? I've have 17" Bullitts that came on the car when I bought it and I don't think previous owner ever corrected the speedo.

Edit: Also, my 18" wheels are staggered. 245/40/18 up front and 285/35/18 in the rear. Which size do I go by for that calculator?

[WhtStang00]

do you need to know stock tire size for the tuner??

and im not sure about the staggered tires since the front is 809 revs and the rear is 804, but if i had to guess i would say that you should go with the rear since we have RWD vehicles, but im really not sure. hopefully someone else will chime in

[mcqueen]

Originally Posted by WhtStang00 do you need to know stock tire size for the tuner?? and im not sure about the staggered tires since the front is 809 revs and the rear is 804, but if i had to guess i would say that you should go with the rear since we have RWD vehicles, but im really not sure. hopefully someone else will chime in

I don't need the stock size, I was just wondering how they compared and how much my speedo is currently off. Considering I've never been pulled over it can't be too far off but I think I'll go with the 804 when I put the 18s on. I was thinking and when I'm on ice and break the tires loose, the speed goes up even if I don't move anywhere.

[WhtStang00]

yeah cause your tires are spinning

[mcqueen]

Originally Posted by WhtStang00 yeah cause your tires are spinning

That's my point, if the speedo is controlled by the rear tires then shouldn't the rear tire size be used with the tuner to recalibrate the speedo?

[WhtStang00]

oh. my bad. yeah thats what im thinking also