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Backstory - 2020 Limited - factory tire size 275/45/22. Did a 6" lift and wanted to keep the stock wheels - in order to use them, I couldn't use a tire wider than 11.5" so I went with a LT295/55/22 which is a 34.6" tall and 11.6" wide.
Anyway, I read to correct the speedometer you can use Forscan to change the size - this is all that needs to be done? I also have a SXT tuner.
That depends. Most of the later model year owners of the 13th gen could change theirs without issue minus doing some calculations to fine tune the accuracy against GPS. My 2016 for example, has a cap where it will not recognize anything higher than a 275/55r20. I tried multiple different methods in Forscan without success when I installed some takeoffs that were 275/65r20 and had to deal with an inaccurate speedo. When I went down to 275/55r20 recently, my speedo was dead accurate on the 3.31 gearing I had at the time and stayed so when I regeared to 3.73s and only changed the axle ratio in Forscan thereafter. I bring up gearing because I have read where some had to change/manipulate the gear ratio in Forscan, in addition to, changing the tire size in order for their Speedometer to be accurate with larger tire sizes.
That depends. Most of the later model year owners of the 13th gen could change theirs without issue minus doing some calculations to fine tune the accuracy against GPS. My 2016 for example, has a cap where it will not recognize anything higher than a 275/55r20. I tried multiple different methods in Forscan without success when I installed some takeoffs that were 275/65r20 and had to deal with an inaccurate speedo. When I went down to 275/55r20 recently, my speedo was dead accurate on the 3.31 gearing I had at the time and stayed so when I regeared to 3.73s and only changed the axle ratio in Forscan thereafter. I bring up gearing because I have read where some had to change/manipulate the gear ratio in Forscan, in addition to, changing the tire size in order for their Speedometer to be accurate with larger tire sizes.
BTW: Nice truck
Thank you for the response. I'll try Forscan and a GPS app to see if its good.
FYI, my speedometer has always been about .5-.75 mph fast compared to GPS. Maybe that's due to tire wear, but I think most speedometers are biased slightly in that direction, so any slight error is biased so you don't accidentally go over the limit.
Speedometer Correction
