Ford Says "Can't Reprogram Tire Size Anymore"

[forddieseldoctor]

We installed a set of OE 20" wheels and tires on a customer's 2012 F-250 yesterday. He had the 18's on it previously. Programed the tpms and then programmed the tire size with the IDS. No big deal, ran it outside and parked it. Customer comes to pick it up and comes inside and says his check engine light is on. Immediately I grab the IDS and go out thinking that all I had to do was the bcm relearn like we had to do on the 11's. Can't find it anywhere on the IDS. Code stored in pcm is a P1635 Tire/axle out of acceptable range. When I looked in the workshop manual it says to perform pmi on the pcm. So I did that, code wouldn't clear. Then I tried the bcm cause that's where the workshop manual shows tire size gets adjusted. Tried going back to the original size all with no luck. Finally I sent the guy on his way for now and sent a request into hotline. They got back to me this morning and the pretty much told me to go suck an egg and that it's not a programmable parameter anymore and that I am going to have to program as-built data into the bcm and pcm to clear the code and then they told me that the customer was going to have to look into an aftermarket option to change his wheel size.

 

[Keith Browning]

Since it used to be this could be done, this is kinda stupid at this point isn't it? Really?!?!

 

I would write back and ask why not as it could be done on prior year models. 

[forddieseldoctor]

I kinda gave up on Ford to give me a usable answer at this point. I have a copy of AE and the plan is to program everything back to stock with the as-built and then use my scanner from home to program in the tire size.

 

But I did find this yesterday. According to the workshop manual I SHOULD BE ABLE TO PROGRAM THE FREAKING TIRES TO THE TRUCK!!!!

 

 

 

[8WA Sman]

My guess is that your larger tire modification my fall under the ESC law (FMVSS 126)of '12. That is if it is 10 k or under. If I had the As Built data from two like vehicles, one with 20" and one with 18" tires I may be able to adjust the data but if anyone asks I would have nothing but blank stare.

[mchan68]

GOOD TO KNOW!!! My truck originally came equipped with LT265/70R17 on aluminum rims. I sold them and bought a set of 20s with brand spanking new LT275/65R20 Michelins to go on them. I had ZERO problems programming the PCM and ABS on my truck to the new tire size when I installed them. Now, just last week I managed to score a set of factory original 18" steel rims with a set of LT275/70R18 snow tires on them. Is this supposed to mean I won't be able to program them when the time comes to switch them out during seasonal changes? By the way, my truck is a 2007 F-250 6.0L 4x4 if that matters.

[forddieseldoctor]

My guess is that your larger tire modification my fall under the ESC law (FMVSS 126)of '12. That is if it is 10 k or under. If I had the As Built data from two like vehicles, one with 20" and one with 18" tires I may be able to adjust the data but if anyone asks I would have nothing but blank stare.

 

That's possible, I did look up the GVW and it's a 9900 lbs ride. The problem with the as-built thing is I don't have access to any vin numbers for near identical trucks.

 

GOOD TO KNOW!!! My truck originally came equipped with LT265/70R17 on aluminum rims. I sold them and bought a set of 20s with brand spanking new LT275/65R20 Michelins to go on them. I had ZERO problems programming the PCM and ABS on my truck to the new tire size when I installed them. Now, just last week I managed to score a set of factory original 18" steel rims with a set of LT275/70R18 snow tires on them. Is this supposed to mean I won't be able to program them when the time comes to switch them out during seasonal changes? By the way, my truck is a 2007 F-250 6.0L 4x4 if that matters.

 

As far as I know it's only the 12 and newer that you can't program.

[8WA Sman]

It's possible that it is listed in SI because doesn't the SD info cover to 450?

[forddieseldoctor]

Up to a 550 is considered a Super Duty.

 

I looked up a bunch of vins from a site that has hundreds of F250's listed on it. So far all of the trucks that have the 20's have 3.55 gears. All of the ones I've seen that have the 18's are the 3.31 gears which is what the truck in question has.

[jimmy57]

It seems that I remember something on the order of, "with fully programmable parameters in the electronics settings can be changed to make it easier to tailor the vehicle to the customers' needs"

 

Except when someone decides you can't anyway.

[Matt Saunoras]

When I put 285/70R17s on my 06 F-250 that wasn't an option listed for tire sizes so I just picked the one that was closest to revs/mile.

 

Now that I have a programmer I can put in the correct revs/mile listed by the tire manufacturer into the PCM.  ABS module remains whatever it was programmed with IDS.

[Keith Browning]

I am actually about to install 20" tires an a 2015 F250 6.2L with stock 18's.    I warned "them." Wish me luck!

[lmorris]

We run into that a lot with the sales department selling new trucks rigged up with bigger wheels. They finally got the picture and stopped doing it.

[DieselD]

I get the aftermarket tire thing, especially when going several sizes either way. What bugs me is when your putting on OEM stuff on a like truck just like in this case. They are using OE wheels and tires on a truck that actually does come with them from the factory but just so happened this one was not optioned this way.

 

I had this issue with my back up camera on my raptor. It was not optioned with one but the plug was there for it. Ford said no way to doing the programmable parameter to turn on the camera function. It would simply be a plug and program deal and on you go with all factory stuff but Ford said you cant do it. Being that I knew this was a BS answer I jumped on ebay and found a raptor of the same year but optioned with the backup camera. Grabbed the vin# and ran the AS-built data on both vehicles. Compared them to each other and changed the data on mine to the ebay vin data truck. Camera worked great after that. Now why couldn't ford add a parameter to turn the camera after the fact???

[Keith Browning]

I am actually about to install 20" tires an a 2015 F250 6.2L with stock 18's.    I warned "them." Wish me luck!

Yep. Got me a P160A hard fault in the PCM - "Control Module Options Configuration Error" but no check engine light on... yet. So I looked into the code for further information and was sent to Relearn Vehicle Information in the Service Functions menu on IDS.

 

 

This procedure DID remove DTC P160A for now. Time will tell.

[BigWalt]

I was wondering, why go by tire / wheel size, why not go by overall height / diameter?

 

example.......

 

OEM tire / wheel

 

285/70R/17 = overall diameter is approx. 32.7new tire / wheel

 

285/55R/20 = overall diameter is 32.3that should not make any differences, shouldn't it? 

[Keith Browning]

Actually, once upon a time we once could choose from a list of tire sizes OR enter the tire RPM or revs per mile on some vehicles though there were upper and lower limits. To determine the correct revolutions per mile for a tire, simply measure the circumference of the tire using a standard tape measure with the wheel off of the ground. Divide the actual number of the tire circumference in inches onto 63360. Round the number up or down to the nearest whole number. This will be your tire revolutions per mile. For example, a tire with the circumference of 85 inches would have an RPM value of 745.

[Matt Saunoras]

I remember being able to choose revs/mile on older IDS calibrations a few years back. Then all the sudden you had a list of available tire sizes to choose from. Now you don't get anything.

 

Is it really that big of a problem?

[Keith Browning]

Matt on this 2015 I had a choice of the 5 or so different possible tire sizes available and you could choose any one of them. Not sure at all why the diesel cant be done but the gasser can. I am holding my breath though.

[8WA Sman]

Keith, What's the axle ratio and GVW of your gasser?

[forddieseldoctor]

We took another swing at this truck. I did the as-built into the pcm and bcm just like hotline told me to. Then I tried to program the tire size in again. I started up and shut the truck off 4 or 5 times. I drove it 5 or 6 miles. Customer came to get it after it sat for about an hour and walked back in the door and said the light was back on. So for now he's running with the old tire size programmed into the truck.

 

I was poking around on the internet last night and came up with a bunch of people on other general diesel forum sites that are claiming that if you program the gear ratio from 3.31 to 3.55 and then program the tire size it will take and you will not see the code again. Which makes sense because when I was snooping around looking for a donor vin I couldn't find one that had both the 20's and the 3.31 gear ratio.

 

My next concern is what's gonna happen when if I program the wrong gear ratio into the truck?

[Keith Browning]

my next concern is what's gonna happen when if I program the wrong gear ratio into the truck?

The same thing as having the wrong tire size programmed - all speed dependent items will be functioning improperly... more or less.

[forddieseldoctor]

Um I don't think it's gonna mess with the speedometer, because the speed is read at the wheel speed sensors. And even if it had the sensor in the diff that reads off of the ring gear which is rotating at the same rpm as wheel speed.

[lmorris]

Could possibly mess with shift patterns more than anything. Most of those guys messing with reprogramming everything will have aftermarket tunes already in the TCM. Do this to a stock unit and you may have issues.

[Brad Clayton]

An auto trans will definitely up shift quicker with a lower gear ratio on a stock tune.

[Keith Browning]

Like I fucking said - these changes all have an effect when you change anything speed related on these late model trucks. PERIOD. My truck... Well let me tell you, after driving for a while you begin to notice that the navigation shows the truck blocks away from where it actually is. I have wasted hours going over this with my new truck with its "new" 20" tires. Engineering is adamant that you cannot change tire size now.