i just recently put on new tires i went from the stock wrangler ap's P255/70R16, to pirelli scorpion at's LT 265/75R16's, as jayntguru stated in another thread that the speedo is not off much, but i have been seeings much worse gas mileage... could it be that the odometer is off cause of new tires, but i wouldn't see why the speedo would be off and not the odometer, it could be the heat and the AC but its not any hotter than before the new tires... i'm just curious if anyone else has noticed significant drop in MPG with new tires....

 

Your new tires have changed your speedometer and odometer ratings. To be exact from a 255/70 to a 265/75 is a 1.59 inch difference in height, and a 5.04 difference in your speedometer and odometer.. So all in all that has affected your speedometer, odometer, and your effective rear end ratio. To learn more about your tire differences go to this tire calculator I use and you cann see for yourself.

http://www.dakota-truck.net/CGI-BIN/TireCalc.cgi

 

thanks for the reply KYFordFreak but when i went to the URL it sent me to a site that had a bunch of code... i would like to know more about this and i'm sure its just my computer but i cannot get to the calculator...

 

www.dakota-truck.net/TIRECALC/tirecalc.html

Hopefulley it works this time. If so just put in the two tire sizes you want to compare click compare Tire A to Tire B and put in your gear info and hit submit.

 

thanks... that last link worked guy... i'm relieved that i'm not getting worse gas mileage... just my odometer is reading less than what i'm actually moving... i know you can get mike t. to design custom superchips to correct this with the computer but can you get a custom flip-chip as well?

 

Yes, to the custom chip flip. It is my understanding that all the flip chips come with custom programming. If you order a regular chip it costs extra to customize it. Actually I just poasted my questions to Mike in the chips section and plan to call him tommorow for more info and maybe to order. If all you want is your speddometer/odometer to be right you may not even need a superchip. Depending on the year of your truck you may still have the speed gear in the tranny that you can change for under 20 dollars. The newer F150's are computer controlled on the speedo and a dealer could possibly recalibrate the truck for you. The only constraint there is they can only calibrate to a Ford offered tire size. What I am thinkin is that they might be able to calibrate your speedo to like the size that comes on a ORP truck. Not sure check it on this board. I know it's on here somewhere.

 

thanks for the info... i just emailed mike t earlier today and i'm just waiting on his reply...