Can I reprogram tire size?

[DaMeatMan]

Hey guy's,

I recently just swapped out the stock tires on my MME4X for some 235/55/R19 Michelin CrossClimate2 tires, and I'm wondering if anyone knows if it's possible to reprogram the car so that it knows the new tire size?

The new tires are slightly larger diameter so this will have am impact on the speed, odometer and efficiency stats, and I would really love it if I can keep that info as accurate as possible after the change. Does anyone know if this can be done from with the vehicle UI via a hidden menu?

 

[phidauex]

I'm very curious about this - I'm hoping to go up about 1" in total diameter for winter tires and would want to reprogram if I can.

Here is an interesting thread on the topic in a Ford truck forum (https://www.ford-trucks.com/forums/1567559-changing-tire-size-for-speedometer.html). Looks like there is a line that can be changed using the ODBII software FORScan, and a clever person created a spreadsheet to help you calculate what value you need to enter.

I know some intrepid users here have been experimenting with FORScan, but I also know that MME support is still in beta and that while it is very likely that tire size is a value in there somewhere, it may not be clear where. FORScan parameters can definitely cause problems or damage if entered incorrectly so you don't want to go poking around willy nilly.

Hopefully someone with more FORScan experience can check to see if any of the "normal" Ford tire size parameters are present.

 

[breeves002]

I wouldn't bother. The difference in full tread to 0 tread on a tire is 0.3" approx. This is barely more than that. In theory it is possible but no one has looked into it yet. It would need to be done with FORScan and you would have to change the as built data for tire size.

 

[Eric_C_Boston]

There is a bigger thread about adjusting tire size at: https://www.forscan.org/forum/viewtopic.php?f=13&t=2650

 

[Carsinmyblood]

Circumference is the only factor to consider re the speedo. A 1.7% change at 60 mph is 1.02 mph. The tire is getting larger, you're going to be off 1.02mph (reading 60 instead of 61.02mph).

A cool excersize, but given that tires change circumference with temperature, wear, air pressure, etc. anyway with nobody noting, I'm not sure I'd bother.

 

[ZuleMME]

Most cars are already from the factory reading 2 to 3 mph higher than they are going. Wouldn’t this help to correct that? Not sure if the MME follows in that regard.

 

[Pushrods&Capacitors]

Hey guy's,

I recently just swapped out the stock tires on my MME4X for some 235/55/R19 Michelin CrossClimate2 tires, and I'm wondering if anyone knows if it's possible to reprogram the car so that it knows the new tire size?

The new tires are slightly larger diameter so this will have am impact on the speed, odometer and efficiency stats, and I would really love it if I can keep that info as accurate as possible after the change. Does anyone know if this can be done from with the vehicle UI via a hidden menu?

Just take the 235s back and get 245/50-19s, they’re the same overall diameter as the 225/55-19s so there will be no speedo error. I believe Michelin specs the 245/50 on a 7”-8.5” rim width as well, so they work with our 19”x7”s. Most tire shops allow returns within 30 days as long as you’re swapping for another set and not getting a refund.

 

[DaMeatMan]

Just take the 235s back and get 245/50-19s, they’re the same overall diameter as the 225/55-19s so there will be no speedo error. I believe Michelin specs the 245/50 on a 7”-8.5” rim width as well, so they work with our 19”x7”s. Most tire shops allow returns within 30 days as long as you’re swapping for another set and not getting a refund.

I would have done exactly that, but the Michelin CrossClimate2 are not made in that size, and the 235/55/19 were the closest match.

I know I could have found another brand tire that did come in that size, however I wanted these tires specifically due to their excellent warm weather characteristics on dry and wet roads, while also offering enough winter performance to also be classified "winter tires" with the 3 peak mountain snow flake rating without having to swap out tires seasonally.

I know there are overall compromises taking place here, but with that said in my Climate in Toronto, Ontario, Canada, we really don't have snow covered roads long enough to justify a dedicated snow tire swap, and those compromises are very small price to pay to avoid the hassle and costs of seasonal swaps and a dedicated set of winter tires.
Insurance companies here also give you a break on rates if you run a three peak mountain snow flake rated tired during a particular time window in colder months, but I find most of that time is spent driving on dry pavement which just eats up snow tires prematurely. So for me these CrossClimate2 were a match made in heaven for my particular climate.

 

[highland58]

I would have done exactly that, but the Michelin CrossClimate2 are not made in that size, and the 235/55/19 were the closest match.

I know I could have found another brand tire that did come in that size, however I wanted these tires specifically due to their excellent warm weather characteristics on dry and wet roads, while also offering enough winter performance to also be classified "winter tires" with the 3 peak mountain snow flake rating without having to swap out tires seasonally.

I know there are overall compromises taking place here, but with that said in my Climate in Toronto, Ontario, Canada, we really don't have snow covered roads long enough to justify a dedicated snow tire swap, and those compromises are very small price to pay to avoid the hassle and costs of seasonal swaps and a dedicated set of winter tires.
Insurance companies here also give you a break on rates if you run a three peak mountain snow flake rated tired during a particular time window in colder months, but I find most of that time is spent driving on dry pavement which just eats up snow tires prematurely. So for me these CrossClimate2 were a match made in heaven for my particular climate.

I have the same tires. I have gone by traffic radar signs that showed me going the same speed as my speedometer showed. This seems to be within the margin of error, not a concern for me.

 

[Eric_C_Boston]

I looked at the as built data for my Mach E and a CA Route 1 that has a different tire. The spreadsheet for the Fusion did not jive with the values I see. It could be the calculation is different or maybe it is someplace else entirely. It will be interesting to see what value the GT has.

Model     Size         Calc  As-Built
Premium   P225/55R19   08AA  1201 or 3502
GT        P245/45R20   08A5
Select/CA P225/60R18   08A1  1231 or 0502

I did notice the following blocks have the VIN.
6F2-01-01 through 6F2-01-04
6F3-01-01 through 6F3-01-04
706-19-01 through 706-19-04
726-04-01 through 726-04-04
733-02-01 through 733-02-04
734-02-01 through 734-02-04
737-02-01 through 737-02-04
760-01-01 through 760-01-04
764-01-01 through 764-01-04
7C4-01-01 through 764-01-04
7C6-01-01 through 7C6-01-04

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