I have a 2013 F-150 4x4 Lariat Supercrew shortbed. I just replaced my factory's 275/65-R18 (32.275" tall) tires with Toyo A/T II Open Country 35" tall tires two weeks ago. Since then, my GPS is giving me turn directions AFTER the fact (late). Dealer said it's because of the taller tires. Dealer said GPS with SYNC uses wheel-speed-sensors to determine where my truck is while navigating. Since a taller (35") tire covers more distance per revolution, my GPS is telling me to make a turn AFTER I've already made the turn. Then it recalculates the route because it thinks I ignored its command to turn. After-market tire dealer said it's a software problem that Ford must fix. Ford said they are "not allowed" to re-program my truck (I'm guessing dealer means the GPS' software). The after-market tire dealer doesn't know what to do. Speedometer also reads slower than my true speed (don't want tickets!). I wondered if an after-market, hand-held tuner would fix these problems, but neither Ford nor the after-market shop knows. Has anyone had this problem? Ford says it only affects GPS units that have the SYNC feature, so they've only had three 2013 owners come in with this problem. I'm sure someone out there has had this problem and can give me the solution (I really rely on my GPS). Thanks!

 

Try disconnecting the NEGATIVE battery cable for a minimum of 20mins. Drive for a bit (50km) and see if the gps recalibrates itself. That worked for my friends 2012 fx4 with 34.5" tires, he had the same gps problem and it was fixed after the battery disconnect. Also the dealer was no help to him either, they told him the only fix was to go back to stock sized tires...

I think it has something to do with the dead reckoning gps system relearning the tires after the pcm is cleared from the disconnect. Please correct me if I am wrong on that.

g0rilla

 

Thanks G0rilla. I will try that and let you know.

 

Thanks gOrilla. You were absolutely correct about disconnecting the battery for 20 minutes to get the GPS to start working correctly. When I put taller tires on my F-150, my SYNC GPS wouldn't work correctly (it was WAY slower than my truck) plus my speedometer was off. One dealer told me there was nothing they could do to fix these because they are set by the VIN. I took it to another dealer who spent two hours (cost me $120) trying to fix SYNC, but couldn't. Then I told dealer about your "un-plug the battery for 20 minutes" idea and it worked!! The GPS now works correctly. Unfortunately, dealer could not fix speedometer, but a performance shop said a tuner CAN fix it - specifically the Bully Dog Triple Dog GT Gas Gauge Tuner - model 40410 @ $399 (based on my tire height; axle-ratio; engine). You fixed a problem that no one else could, so, for that, I am very grateful.

 

how about a pic of your truck with the new tires ....did you lift it at all?

 

Yes – I had a 4.5 inch BDS suspension lift kit installed - which included FOX shocks on the rear. This is the only way I could get 35 inch tires to fit. I like this lift kit because it maintains the factory geometry and ride quality. I will attach a photo of my truck next time I get on my PC.

 

Question? Does your lift require any cutting of the frame or cross-members? I want a 4" lift so bad, and also want to fit 35's, but am not willing to cut the frame on a truck with a $52,300 sticker price. The way I look at it, ford spent countless dollars and man hours engineering the frame to a certain spec. I don't trust an after market kit, to be held to the same standard or tolerances.

 

Not sure about the GPS issue, but a programmer can recalibrate your speedo, make sure it specifies tire / wheel calibration. I have a superchips Cortex, it states it has the capability, I have never used that feature though. I don't understand the GPS issue at all though, I thought it had nothing to do with tire revolutions, a GPS is supposed to use satellite positioning to know where it is at, regardless of how fast your tires are moving, it should be measuring from how fast IT is moving. You might try going to the Ford Owners website and download an update if one is available. Other than that, I don't know, that's a new one on me. Keep me posted on the cause / remedy.

 

Forget my earlier reply, should've read further, that is a nice piece of information to know about disconnecting the battery.

 

When they returned the removed factory suspension parts it appears that they cut two large metal pieces off of the front frame. I don't know what the parts are called, but it does look like they had to cut off two pieces of the front framework or crossmember. I was impressed at how thick the metal is on the BDS suspension lift kit. Even with a 4.5 inch lift kit, my 35 inch tall Toyo tires come within an inch of hitting the inner wheel well on the front when the wheels are fully turned in either direction, so I don't know if you can get away with a 4.0 inch lift or if you will need to go to a 4.5 inch lift (probably depends on whether you're running a true 35 inch tall tire versus a 34.5 inch tire or a 34.0" tire (some 35 inch tires are actually in the 34 inch range however, my Toyo tires truly are 35.0 inches tall

 

Sync / GPS software is up-to-date – per the dealer. I agree with you that the GPS should be based on the satellite antenna and not on the size of the tire. The first Ford dealer I went to told me the GPS operates off all the satellite and the wheel speed sensors. Apparently that was not correct since they fixed the GPS and I don't think my aftermarket wheels even have the wheel speed sensors. I'm looking at a bully dog tuner that can be programmed based on the tires revolutions per mile as well as the axle ratio.

 

where`s that picture

 

Badmouth, does your GPS/SYNC still work correctly? I have a 2013 F350 that is having to same issue after slightly larger tires.