tire size affect tune
04-08-2008, 05:30 PM
#1
tire size affect tune how does the pcm know what size tires i have on it?
people are telling me if i put on 28's (cars tuned for 26's) that it will shift early
simple question is idk how the car knows what size tires it has i dont see how it will change at all
oblivously my speedo is off...but if its set to shift at 40mph from first with 26, it might be going 45 but the speedo will still say 40 when it shifts...same with the tach...i dont see how it will shift early?
people are telling me if i put on 28's (cars tuned for 26's) that it will shift early
simple question is idk how the car knows what size tires it has i dont see how it will change at all
oblivously my speedo is off...but if its set to shift at 40mph from first with 26, it might be going 45 but the speedo will still say 40 when it shifts...same with the tach...i dont see how it will shift early?
04-08-2008, 06:12 PM
#2
TECH Fanatic
Join Date: Feb 2004
Location: Lexington, KY
Posts: 1,259
Likes: 0
Received 0 Likes
on
0 Posts
It's the same thing as changing gears without reprogramming it. It will still shift at the same speed as it did before according to the speedo. But the speedo will be off so it's not shifting at the speed that it thinks it is. It would be noticable when driving.
04-08-2008, 06:35 PM
#4
TECH Fanatic
Join Date: Feb 2004
Location: Lexington, KY
Posts: 1,259
Likes: 0
Received 0 Likes
on
0 Posts
For WOT shifts I agree it's best to go off RPM only. I was mainly referring to part throttle shifts. Either way you have to tune it to adjust for the different size tires or there will be side effects.
Trending Topics
04-10-2008, 05:08 PM
#8
TECH Regular
Join Date: Aug 2004
Location: Tyler, TX.
Posts: 443
Likes: 0
Received 0 Likes
on
0 Posts
RPM lied to you because i have several cars including 2 of my own that are running that way with no problems. Just make sure you dont zero out the part throttle up shifts and only do the full throttle up shift table.
04-12-2008, 12:20 AM
#10
TECH Regular
Join Date: Aug 2004
Location: Tyler, TX.
Posts: 443
Likes: 0
Received 0 Likes
on
0 Posts
I have dealt with RPM on many occasions and they are great guys just not eager to listen to what somebody else has to say. Its hard to get a tune out of them that you request how u want it. All they want to do is give you a WOT tune and send you out the door for $400. It sucks cause they are such a great group of guys to give such shitty tuning customer service.
04-12-2008, 11:31 PM
#11
ya i specifically mentioned it and they guy actually did a bunch for me for cheap...but he told me that didnt work all the time...i said well i should try it at least and he said it just doesnt work..lol
i still dont see why it even messes with shift points
i still dont see why it even messes with shift points