Attention: TDR Forum Junkies I just replaced my factory 265's with 315's and called the dealership to see if they could recalibrate my PCM. They said "no problem, it'll take about a half hour and run ya $32. 50". Well, when I took my truck in, they said it couldn't be done 
. Then they started messing with it and after a half hour or so said "we're still trying some things, it's gonna run you at least $65". They ended up having to call the training department, who told them how to set the revolutions per mile, yadda yadda yadda. After 1 1/2 hours, they finally said my truck was done and calibrated. Only charged me $32. 50... right then I shoulda known something was up. When I left, my speedometer still didn't seem right. The next day, my 60 mile round trip to work showed up as about 53 miles. This morning I checked my trip odometer against the mile markers on the turnpike, and for every mile I traveled, it showed 0. 9. I'm pretty sure the speedometer is off too, since it was reading under 70 the whole way to work and I was still on time 
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I think tomorrow I'm gonna go in there with a chart of both driveshaft and wheel revolutions per mile for the calculated diameters of the factory tires and the 315's, and possibly for the measured diameter of the 315's too. Without letting them touch anything without me watching, I'm gonna look over their shoulders while they show me what the revolutions per mile are set to. Then when I see that nothing has changed, I'm gonna talk to the manager, tell him that if he checks his records, I've spent over $60k there in the past 2 years, and will own a viper by 30. And ask him if he wants to lose a customer like that over dishonesty with a $30 service. If nothing else, I better at least get my money back (to take to another dealership). Hopefully they'll fix it right, for free. Maybe if I talk to the manager in the showroom, in front of alotta customers, he'll give me a free set of nerf bars to make things right
Anyway, anyone else who's had their PCM recalibrated, how close did they get it? mine's off by about 10%, and from what I can tell is still using the factory programming
. Then they started messing with it and after a half hour or so said "we're still trying some things, it's gonna run you at least $65". They ended up having to call the training department, who told them how to set the revolutions per mile, yadda yadda yadda. After 1 1/2 hours, they finally said my truck was done and calibrated. Only charged me $32. 50... right then I shoulda known something was up. When I left, my speedometer still didn't seem right. The next day, my 60 mile round trip to work showed up as about 53 miles. This morning I checked my trip odometer against the mile markers on the turnpike, and for every mile I traveled, it showed 0. 9. I'm pretty sure the speedometer is off too, since it was reading under 70 the whole way to work and I was still on time . I think tomorrow I'm gonna go in there with a chart of both driveshaft and wheel revolutions per mile for the calculated diameters of the factory tires and the 315's, and possibly for the measured diameter of the 315's too. Without letting them touch anything without me watching, I'm gonna look over their shoulders while they show me what the revolutions per mile are set to. Then when I see that nothing has changed, I'm gonna talk to the manager, tell him that if he checks his records, I've spent over $60k there in the past 2 years, and will own a viper by 30. And ask him if he wants to lose a customer like that over dishonesty with a $30 service. If nothing else, I better at least get my money back (to take to another dealership). Hopefully they'll fix it right, for free. Maybe if I talk to the manager in the showroom, in front of alotta customers, he'll give me a free set of nerf bars to make things right
Anyway, anyone else who's had their PCM recalibrated, how close did they get it? mine's off by about 10%, and from what I can tell is still using the factory programming
Of course, now you have to find someone willing to spend the time and experiment. Good luck! And don't hold yer breath:-laf
