I just bought 2001 F150 Lariat Off road 4X4 5.4L. It came with 20" 285-55-20panther wheels. Also came with factory 17' rims and tires. 235-75-17. I just put factory 17" wheels for winter, Do I need to adjust my speedometer if so how do I do this. I dont know that much about mechanic language so simple language would be helpful. Thanks for the help.

 

as long as your overall tire diameter is the same or within .5-1" i wouldnt worrry about it. Either compare rims/tires next to eachother, or you can drive 10 miles on the highway, watch mile markers, and see how close you are on your odometer to 10 miles.

But to answer you other question, there isnt a whole lot you can do with a stock truck to recalibrate the speedo, since its not just going to be off, its an actual ratio its off by.
-Patrick

 

Just to let you know, I went into the dealer to ask the cost for changing the speedometer since I put on taller tires. They want $90 bucks for it. highway robbery for a 10 second computer update.

 

The best solution is to buy a tuner that gives you the ability to adjust it yourself. The $90 to $100 the dealer charges is a good start on paying for a tuner.

 

well on 97-03s you cant just change the computer update to my knowledge, only think you can update is gear ratio from 3.31, 3.55 or 3.73s since 4.10s werent a factory option until 05 i think.
-Patrick

 

Not sure what you are responding to, but with the Edge, can you not adjust for different tires sizes for those years?

 

yah but he nor i have the edge. Im saying with a factory set up, there is very little he can do....

 

yeah the 97-98s had mechanical gear driven speedos, but 99-present are computer controlled, so there really is no cheap solution for this poor guy.

 

ok, and yes you are correct. he has to reprogram.

 

Thanks for your help, I am so happy with my truck and after i found this forum i think i made right decision with ford f150. You guys are awesome. Before I bought this truck, i was almost going to buy dodge ram 1500. You guys made me happier with my desicion.

I will test my speed with my gps, i dont think its going to be big difference. i will not spent big bucks just for speedometer. I think i am not the only one with this issue and most people dont even think about they will have speed difference. Only problem i have microsoft street and gps so i have to hook up my laptop and somebodyelse must be present with me.

 

I went from the 265/70/17 to 285/70/17 and noticed very minor changes, probably under 5%, but one day I will true it up with the Ford Speedometer recalibrator that I bought. $100 off ebay and all said it's pretty easy to install. I haven't done it yet but when I do I'm good for any change that alters the speedo. Gear swaps, taller still tires, you name it. Switch some switches in the box to corresponding chart in instructions and bam!!! All set. Just gotta make sure the connection is proper, there are 2 different recalibrators, a -t99 (mine) and a t01, for 2001 and newer.