Hi guys spoke with the dealer and told them I wanted to up the tire size from 275/55/20 to 305/55/20 and was wondering if it would throw my spedo out by much. He then told me that going to larger than stock tires would screw up my ABS and Advance Track. His line was the computers on the new trucks are very sensitive to changes. I see lots of peeps with bigger tires so I am skeptical.

Thanks

2012 FX4 SCREW 5.0

 

He is pulling your leg.

 

Yup he's a leg puller. If its so sensitive then why did Ford team up with Tuscany auto to make a black ops addition f-150 that has 35"

 

The dealership where I got mine is puttin my new wheels and 35 inch tires on Monday and they are also recalibrating my spedo at the same time he is just messin with you

 

Thanks guys.

 

That isn't much of a difference in size anyway. I have 305/55 20s on my truck.
Compared with my GPS, my speedo is very close to actual speed.
At 70mph, its consistenty off by 1 mph. Not even worth recalibrating IMO.

 

Tell dealer to check out the forums so he may learn something. No problem's going from the stock Pirelli's on mine to 305x55's. Anything is possible with the ABS and AdvanceTrac and a computer. Ask him what's the trick with running 35's on a Raptor from the factory!

 

Spoke with a different dealer, this one said no problem on running bigger tires but I would have to flash the puter with the new tire size. Something they will do for $120.

Don't know what the first dealer was on, but he was parts and not service but still. I went with 285/55/20 for now. I'll look at bigger tires when I do the 3 inch lift.

 

He is not entirely wrong... changing tire size will change the ability of the ABS/Traction control system to properly control the vehicle.

But it is a minor change.
It will not "screw up" anything. It might just reduce the efficiency of the system slightly.

The system is tuned to handle the stock tires in the stock sizes.

Changing to aftermarket tires of the same size will also change the performance slightly.

Long story short - you will be OK.