Folks...been searching like mad and can't find any definitive info on this one.

My truck has the stock 20" Pirellis, which aren't a bad tire, but don't have quite the amount of stiffness I want when towing a heavy load. I'm just looking for something a little more stable. So I've decided to swap them out for a set of LT rated tires that will allow much higher tire pressures. My question is what impact will this have on the TPMS? Has anybody else done this kind of upgrade, and did you have to switch sensors or reprogram the computer? Is it even reprogramable? Any help would be appreciated.

 

I found the 20" Pirellis to be a poor choice for a tire on my 2011 F150 XLT supercab. I decided I wasn't going to wait until they wore out and needed to be replaced, so I swapped them out at 2K for Michelin LTX M/S2's (P275/55R20). I found the ride and handling to be like night and day running them at the Ford recommended pressure of 35# all around. I ran the Pirellis at 35# also but I absolutely hated them. I made no changes or adjustments to the system because of the tire change. How much higher do you want or plan to set the tire pressure? Why would you want to exceed the mfg's recommended setting?

 

What size Michelin did you put on? If you used the stock size 275 55R20 it would be a P rated tire and run at a lower pressure (44 psi max). I went with the LTX AT2 LT285 55R20 which has stronger side walls and a much higher max pressure (80 psi). My plan is to start at a baseline of 50 psi and adjust up or down from there for routine driving, and air them up to around 70 psi when towing. Not looking to increase my truck's payload. Just looking to better manage what I have.

 

Though I don't have a definitive answer nor insight into FoMoCo's algorithm, from a lot of reading I don't think it will matter and/or affect the TPMS.

A sensor is tripped when the PSI is 25% less than an acceptable range.

More than likely the recommended P tire PSI and that of the LT are within the same range. The "over inflation" condition caused by a LT with a load would not trip the TPMS (it monitors under inflation).

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Sorry....completely brain farted that on the first read. My response is still applicable in that I'm using a different type of tire.

 

THAT, is the answer I've been looking for myself. I upgraded to LT's, and wondered the same thing. Thanks Joe!!

 

Yes, I stayed with the P275/55R20. The max pressure rating on the side wall means just that, max pressure, not the recommended pressure. With the pressures you are looking at, I can only imagine the stiffness of the ride let alone the handling. Tires that hard would rattle the crap out of my kidneys and loosen every kidney stone I have in them. LOL. BTW, not looking to argue, just trying to understand.

 

That's what I've been hoping, but I found several references to 25 psi and 50 psi computer settings depending on what the truck came with OEM.

 

So did you air your LTs up yet? And did you get any TPMS dash warnings?

 

I get that....no worries. I know I'll be sacrificing some of the ride quality, but I prefer a little more road feel. Even with the Pirelli's aired all the way up it's too soft now for me. And limiting the sidewall roll under load will help the tow handling. 50 psi in a LT tire should be ok for daily driving.

 

No, not yet.
When I had these tires installed, Belle tire recommended to stay at the 35psi. They said the higher pressure would screw up the TPMS. Something just didn't sound right, and I tried to get an answer for quite awhile. Even the truck dealer was no help, imagine that. What gMDJoe said makes sense.

 

I should get mine delivered by Tuesday and will hopefully have them on the truck by next weekend. I guess whichever of us get to try to air them up first can post the results.

 

$10 says you'll beat me to it. LOL I'll be working dark to dark all week.I've got zero tools other than a cordless drill/driver down here at my wife's house. Can you believe all the gas stations around here charge .75 for air?

 

Don't mind being the mule. Maybe someone else who's already done it will pop up.

 

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