brulaz

Thinking about putting some new tires on my 20" wheels that would increase the overall diameter to 33.5"

All the F150 tire/wheel combos (18", 20" and 22" wheels) that I've checked are 32", but I understand that Ford dealers can re-program the computer to work with some other wheel/tire sizes, but not sure which ones.

Anybody know if the truck's computer can be re-programed to a 33.5" diameter? Or something within a percent or so?

FX4ord

If you find a way to reprogram and are obsessed with accuracy, you should reprogram to the tire's actual physical size, not the manufacturer's advertised size. Not the numbers molded on the sidewall. Tires never live up to their published dimensions. It's all about marketing.

brulaz

Well that would be even better. But it's my understanding that the Dealer can only re-program to stock Ford supplied tire sizes, not some arbitrary number; and I was wondering if there was one that was close to 33.5" diameter. Doesn't really matter which tire/wheel combo it is, it's just the diameter that's important.

azmidget91

Any programmer will adjust your speedo for aftermarket tire size or gear ratio. The dealer should be able to do it as well

motox151

275 55 20 is in the Ford IDS for example. If IDS Doesn't have the exact size you want it can get you close via diameter especially since its just a 33, if you want exact get a programmer

brulaz

Thanks folks. Didn't realize there were aftermarket programmers out there that could do this. Will look into that.

paulson7433

Correct me if I'm wrong but it looks like you've got an economist and I don't think there is a programmer for those. If there is can someone tell me who makes it?

brulaz

No Economist but I do have the EcoBoost.

paulson7433

Ha. It's Friday man I don't have to be on my spelling game and this stupid phone thinks it knows what I mean.

brulaz

Some day it will.

Anyway, I don't think the engine computer would be involved in wheel diameter settings?