Custom Tune Conundrum
#2
Nope, it's made to be messed with. Just figure your tire size and about 3-5% "squish" factor on the tire and input the number. The dealers can do it, but it'll only be for the stock tune and cost about $80 to do. Really no point since you have a programmer to go that way.
#3
Originally Posted by otto457
Nope, it's made to be messed with. Just figure your tire size and about 3-5% "squish" factor on the tire and input the number. The dealers can do it, but it'll only be for the stock tune and cost about $80 to do. Really no point since you have a programmer to go that way.
#4
How large of change from the original tune did you make in tire size? Even so with the change (keeping the same line pressures as are written in the tune), it shouldn't affect the shifting too much if any. If they are vastly different tire/wheel sizes the changes would mostly be felt in changing the final gearing.
#5
Originally Posted by otto457
How large of change from the original tune did you make in tire size? Even so with the change (keeping the same line pressures as are written in the tune), it shouldn't affect the shifting too much if any. If they are vastly different tire/wheel sizes the changes would mostly be felt in changing the final gearing.
#7
Originally Posted by otto457
If it's off by 1 or 2 mph compared to a GPS I wouldn't worry about it. If it's more than that then I'd be worried.
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#8
Senior Member
After I changed my tire size mine is off about 2mph. When I put in my tire size the tuner rounded up for some reason so I knew it would be a little off any way. Also when I changed the size the shift points changed a little. Noticed it mainly in shifting to overdrive, used to shift when speedo got to 40 mph and now shifts at 45mph.