How do I adjust the speedo

Fandini · #1 (**permalink**) 11-16-2008, 11:20 AM

Got some new tires, Toyo Open Country A/T, 285/75 R18. Up from 275/70 R18. Is there any way to adjust my speedo, to offset the 3-4 mph difference at 70 mph. Can't they adjust it in the computer at the dealer? My truck is a 2006 F-350 PSD w/ torqueshift auto trans.

jhaddox · #2 (**permalink**) 11-16-2008, 11:26 AM

i know you can with the sct i just dont know how to figure out rev/sec or w/e it calibrates it as...i know theres a few things you can buy that will recalibrate without a tuner...maybe someone with some more info can come help ya

TANK'S 250 · #3 (**permalink**) 11-16-2008, 11:54 AM

The dealer can do up to a 35" tire

Fandini · #4 (**permalink**) 11-16-2008, 12:16 PM

The OEM Tires were supposed to measure 33.1" in diameter, the new ones spec at 34.8" in diam. I guess that would qualify for a dealer adjustment?

TANK'S 250 · #5 (**permalink**) 11-16-2008, 12:21 PM

yup...it's under 35"

rbloodhound · #6 (**permalink**) 11-16-2008, 12:40 PM

Also the SCT does not adjust the speedo. The revs per mile is to adjust the transmission shifting.

***HeavyAssault*** · #7 (**permalink**) 11-16-2008, 01:32 PM

Go to the dealer or buy an aftermarket box.

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