Speeding Ticket Waiting to Happen
#1
Junior Member
Thread Starter
Speeding Ticket Waiting to Happen
Just curious.. Just bought 03 F150 XLT and coming home from work noticed I was passing everybody. Cruise set on 74 as usual. ( Interstate travel w/ speed limit 70) then it dawned on me... Truck set up for 16" tires and I'm running 20" now. Figured speedo was off. Opened my Waze app on phone and speedo was 7 mph off. I was actually running 81. I was told some GM's you can reprogram computer for different size tires , can it be done on Fords too?
#2
So many things wrong here. 1- you didn't have 16" tires. They are called rims. 2- rim size won't change speedometer calibration. Only tire size. So for instance if you had a 33" on a 16" rim, then ran a 33" on a 20" rim it's still a 33" tire. Yes you can reprogram the speedometer with a programmer.
#3
Senior Member
My kids bike has 16 inch tires
#4
Senior Member
Easy now guys! Is it possible that when you started running 20" rims that your new tire diameter increased? If so then that would cause the speedo to be off.. Say If you went from stock 16" rims with 265/75 tires to a 20" rim with 295/55 tires.
Yes you can reprogram the computer for tire size. You will need a Programmer like SCT or Edge.
Yes you can reprogram the computer for tire size. You will need a Programmer like SCT or Edge.
The following users liked this post:
djl5625 (07-10-2016)
#5
Senior Member
Also your speedo is not off by MPH. When you're not moving it's not saying you're going 7 MPH. It's off by a percentage. For example, when I'm going 50, my speedo says 43 so I know my speedo is 14% off.
Trending Topics
#8
Senior Member
Tyre size calculator shows an 11.1% difference between stock and your current size
also shows 70=77.8 so yup you are roughly 7mph out as expected
also shows 70=77.8 so yup you are roughly 7mph out as expected
The following users liked this post:
djl5625 (07-10-2016)