4.10 gears installed now I have a few ?s

[BackinaStang]

After I installed my 4.10s I reloaded my SCT brenspeed tune and made the gear ratio change and changed the revs per mile for the upgraded tires. My speedo doesnt seem to be reading right seems like Im going 15 mph slower than what im reading. Im wondering will the tuner allow me to make several changes at once or do I have to do them one at a time? The last change i made was revs per mile so if thats the case maybe it only read that last change, is this right or should it have taken both of the changes? Also for the guys running 4.10s in thier 5 speeds what RPM are you running at 60 in
5th?

 

[gmantheman]

I am not sure about the SCT but with the diablo you can make several changes before loading the tune. At 60 MPH my RPMS are around 2100. And my rear tire size is 285/40/18 which is about 27"

 

[BackinaStang]

Thanks I found out whats wrong. I made a bonehead mistake and punched in 630 revs instead of 730 revs. Im back on track now. Im running 2000 rpms at 60 in 5th with 245x55s R18 in the rear. Just wondered if everyone else was close. Gunna check speedo with gps later to verify its correct. thanks again gman

 

[gmantheman]

Thanks I found out whats wrong. I made a bonehead mistake and punched in 630 revs instead of 730 revs. Im back on track now. Im running 2000 rpms at 60 in 5th with 245x55s R18 in the rear. Just wondered if everyone else was close. Gunna check speedo with gps later to verify its correct. thanks again gman

What I found to be spot on according to my GPS and those "Your Speed" sign is tire revs per. mile X 1.03(for the load). Are you sure your tire is 245/55/18 and not 245/45/18?

 

[BackinaStang]

Yes I went taller on tire to get my gear where I wanted it thats why my rpms are slightly lower