Has anyone had a problem reprogramming the PCM to recognize larger tires? I just got off the phone with the dealer where I bought my truck and they told me the PCM won't recognize the larger tires because it wasn't an option for the truck?!?!? They are Raptor tires (315/70/17) so they are a stock Ford piece.

Crazy part is...they did a truck with suspension, exhaust, tires, and the service manager said they were able to do theirs!!! The tires and wheels are aftermarket pieces but not sure of the size. WTF?!?!?

I know it isn't a big deal, but I want the speedometer to be reading correct instead of always doing the math to figure out mileage and road speed.

I may just try another dealer and see how I make out. Any help would be great.

 

They should be able to flash the PCM with 607, see post here:
https://www.ford-trucks.com/forums/1...l#post13601518

 

Makes sense to me, but they said the truck wouldn't take it???

I'm calling BS!!!

 

I'm calling BS too because my local dealer sends about 6 trucks per year out to be upfitted with huge tires, lifts, etc.

 

You shouldn't have to go thru the expense, but purchase an aftermarket programmer.

As everyone else has stated, dealers are always selling trucks with lifts and tire mods, especially down here, they even advertise that the speedo has been reprogrammed for the tire / wheel combo.

 

This keeps coming up. Unless something has changed recently the only options the dealer has selectable are the tire sizes that were available on your truck from the factory. That is your VIN. Not all the sizes that are available on the entire F-150 line including the Raptor. They don't just type in a size, there are listed sizes to select. So, since you couldn't order Raptor tires when you ordered your truck, that size will not be listed.

Not sure how these dealerships that are modding new trucks and selling them are doing it.

 

Aftermarket Programmer? Not sure, never had a reason to ask. Most guys that I know that have modded their trucks used a programmer. I just know that the salesmen down here are quick to tell you the speedo has been recalibrated when they are trying to sell a (new) truck with larger the OE tires. I have never drove one and compared it to a GPS either, so they may not have them recalibrated.....

 

That's what I was thinking. I have heard too many people take their trucks in and $100 later the dealership says there are done an didn't appear to change anything.

Either way, they are not using the stock Ford programming to correct for large oversized tires.

This has been a known issue since at least 2011.

 

Like I said, I've never really thought about it until reading the posts on here, the only logical thing I could come up with is an aftermarket programmer. You're probably correct, how many folks, in the car buying process will think at that moment during a test drive, to compare it to a GPS, with smartphones it isn't that difficult. Me personally, If I purchased a New truck with mods, I'd notice if it was off a week or so later! (then purchase a programmer and fix it)!

 

My local dealer sends the trucks out to be upfitted and the company that mods them owns and supports parts of the new truck warranty. If I were the company being hired to mod several trucks per year for all the local dealers, I'd definitely own the programmer that adjusted the speedo.

 

OK...with that being said, could they reprogram for a different rear end gear?? The Raptor tires are 7% off by calculations. My truck has a 3.55:1 rear gear, so, 7% higher gear would be approximately a 3.31:1 gear ratio. That would get me a lot closer, maybe not perfect, but closer to accurate.

 

I have only heard of this being done once on a 2011 F-250. The problem is that it will also effect all your shift points. The main reason that it was done in that case was because 20" wheels were not available on an F-250 with 3.31 gears and 20" wheel sizes were the the selections needed. Not the case in the F-150. Personally I wouldn't go this route.

Remember you can select any tire size that you could have ordered. If you have 18" wheels you can still select a 20" wheel if it gets you to the correct diameter.

Otherwise I would go with a programmer.

 

Looking at the tire options I think you will need to go with a programmer. Your tires are 34.36" diameter, the largest diameter you can put in is 32.07" with 275/65/18. The 20" are actually a smaller overall diameter.

Unless there is a way to select the Raptor sizes I think a programmer is the way to go.

 

^^ Second that.

 

Not helpful to the OP but, for anyone who is reading this and only planning to go up one size from the existing factory size, a reflash shouldn't be needed.

I called my dealer today and talked with my service adviser. I explained t hat I'm planning to move up tot he P265's from the P235's and said t hat a reflash is not needed.