speedometer adjustment for tire size

[Jozef Zoldos]

I have a 2011 Expy EL Limited and I just placed on a lift kit and changed wheels/tires to LT295/70/18. What is the best way to adjust the accuracy of the speedometer?

 

[jeff kushner]

I know for motorcycles and scooters, there are programs that will run the calcs, just fill in the blanks .................google will be your friend here. I trust that there will be no shortage of tire retailer-sites to help<LOL>


As I remember, the gearing programs needed tire size.....by running it leaving the gearing constant, that would give you the delta you are looking for.
Good luck,

jeff

 

[Vancouver Bob]

I ended up buying a used programmer off Craigslist and used that to adjust the speedo. I had to get online and pay to get have the programmer reset so that I could tie it to my Expedition.

 

[1970Maverick]

here is a tire sizing site that compares
specs, actual speed, gear ratios and much more to find the right tire for you.
https://tiresize.com/tiresizes/225-45R18.htm compare tire sizes

 

[intense98neon]

I believe you can adjust the tire size in Forscan if you know the circumference of the tire.

 

[Jozef Zoldos]

I believe you can adjust the tire size in Forscan if you know the circumference of the tire.

Thanks all for your help.

I just downloaded FORScan and purchased an OBDLINK EX adapter. I scoured the internet and there does seem to be some references out there to adjust the speedometer. Here is a link in case anyone is interested:


I am new to FORScan and I would like to learn more. Does anyone out there know about a good link to FORScan spreadsheets for a 2011 Expedition and/or a link to help me figure out versatility of this product? e.g., Is it possible to measure my transmission temperature with FORScan?

 

[intense98neon]

I'm not sure if this will work for the 2011, I have a 2017. You could always look in Forscan and see if the information matches up.

https://docs.google.com/spreadsheet...TKARDo2Y7lfSOMFj6Gott8g7yg/edit#gid=756156726

You can read the transmission temperature with the OBD2 adapter and the Torque app, that is what I do.

 

[Jozef Zoldos]

I looked. It does not work for 2011. Thanks for your attempt

Any other suggestions would be appreciated.

 

[Munkiebunz3]

Don't do it. With larger vs stock you get free miles (more distance coverage vs what the odo actually says). Just learn the mph table for the new tire sizes.

 

[Frank Wilson]

Don't do it. With larger vs stock you get free miles (more distance coverage vs what the odo actually says). Just learn the mph table for the new tire sizes.

Shssssssh. If you ever sell.

 

[Munkiebunz3]

Shssssssh. If you ever sell.

Well that's when you calibrate it....

 

[aagitch]

I haven't been able to find out how to correct/change speedometer for wheel change. I'm getting ready to upgrade to 20" from 18". Any one know? thanks The spreadsheet in the post above shows where you can mess with it but doesn't show what change. Will I get a DTC or warning light of any kind if I don't even bother to mess with it?

 

[07navi]

Probably illegal because miles when you sell.

I bought an old laptop just so I could use Forescan (mainly to get rid of tpms light) for some sellers are saying Forscan won't work with a 2007 Navigator. Does anyone know anything about that?

 

[aagitch]

Theres a ford tire size guide for forscan that I found that's shows what code I need for the new size tires etc..

 

[bobmbx]

I haven't been able to find out how to correct/change speedometer for wheel change. I'm getting ready to upgrade to 20" from 18". Any one know? thanks The spreadsheet in the post above shows where you can mess with it but doesn't show what change. Will I get a DTC or warning light of any kind if I don't even bother to mess with it?

If you're only changing rim size, but have the same diameter tire, you don't need to change anything.

 

[chuck s]

What Bob said. Got nothing to do with wheel size but everything to do with tire size. All the standard wheel/tire sizes use the same speedo settings.

Original equipment tires have a diameter ranging from 31.9" (20" wheel) to 32.1" (18" and 22" wheels) -- Essentially all the same diameter regardless of 18", 20", or 22" wheels ("rims" if they're gaudy enough). About 3 revolutions/mile max difference -- no speedo change needed and makes sense from a manufacturing stand point. Customer wheel size makes no difference with the selected OE tire sizes.

Going to non-standard tire sizes can have some ramifications.

-- Chuck

 

[aagitch]

Thanks for the explanation. Definitely makes sense