Tire Size Change

[Guggenheim99]

Going from a 245/75-16 to a 31x10.5R15 with my FX4 wheels I acquired for my 02 Ranger. Does anyone know how to change the size with Forscan? I have looked online and really only saw threads for the new rangers. Also would the size be stored in the ABS module? PCM? Should I even bother if the speedometer will only be off a negligible amount? Thanks

 

[slater50]

Did you already buy the tires?
265 75 15's are MUCH lighter than a standard 31" & pretty much sizing is identical.
Lighter due to load rating is less, & will have a nice ride quality...

If youre not doing severe off-roading, no downside to the metric equivalent...

 

[4x4junkie]

245/75R16 comes out to 30.47" diameter... Most 31x10.50s are around 30.7-30.8". If anything, that actually might make your speedo slightly more accurate because most OEM speedo calibrations read about 3% fast to begin with.

 

[sgtsandman]

Going from a 245/75-16 to a 31x10.5R15 with my FX4 wheels I acquired for my 02 Ranger. Does anyone know how to change the size with Forscan? I have looked online and really only saw threads for the new rangers. Also would the size be stored in the ABS module? PCM? Should I even bother if the speedometer will only be off a negligible amount? Thanks

There isn't enough of a difference to matter. Updates for tire size on the older Rangers, while possible has been nebulous. A dealer is supposed to be able to do it. Finding out how to do it with forscan has been a problem. One is supposedly able to do it but I haven’t found out how yet.

With the change you are looking to do, it will be in the buffer the system already has in it. Fords tend to read about 2 mph faster than they are actually going in factory configuration. I went from reading about 2 mph faster with 235/75R15 tires to about 3 mph slower with 31X10.5R15 tires. As long as you try to keep to the speed limit or go with the flow of traffic, you shouldn't have a problem. Unless you run across a crusader who is nailing everyone going faster than the posted speed limit. Not a common thing but there are some out there.