Why are you running the 255/45/20 tires?

[bpd1151]

That is not an opinion.

I sleep with a master certified service adviser who has also spent some time working in the warranty department.

This is a real issue that can and does damage the AWD system. I can also assure you if you have a PTU failure with this setup under warranty, you should be prepared to pay for a PTU.

"Major dissimilar tire sizes between the front and rear axles could cause the AWD system to stop functioning and default to front wheel drive or damage the AWD system.

That quote is from my owners manual.

So which is the haphazard opinion?

I honestly don't care who you sleep with. TMI bro.

But I am at 66K on the clock. Still original trans. Still original PTU.

Your opinion is just that. An opinion.

If I had failures of my own, then perhaps I'd consider your (owner's manual) doomsday prophecy with some degree of weight. But again, no issues here.

Different tire sizes (than factory recommended) as well as staggered. Still roll'n strong my friend.

If we all followed the nomenclature of the owner's manual, than none of us, including you, would modify in any way, shape, or form.

Carry on good people. 

[FoMoCoSHO]

That is not an opinion.

I sleep with a master certified service adviser who has also spent some time working in the warranty department.

This is a real issue that can and does damage the AWD system. I can also assure you if you have a PTU failure with this setup under warranty, you should be prepared to pay for a PTU.

"Major dissimilar tire sizes between the front and rear axles could cause the AWD system to stop functioning and default to front wheel drive or damage the AWD system.

That quote is from my owners manual.

So which is the haphazard opinion?

I honestly don't care who you sleep with. TMI bro.

But I am at 66K on the clock. Still original trans. Still original PTU.

Your opinion is just that. An opinion.

If I had failures of my own, then perhaps I'd consider your (owner's manual) doomsday prophecy with some degree of weight. But again, no issues here.

Different tire sizes (than factory recommended) as well as staggered. Still roll'n strong my friend.

If we all followed the nomenclature of the owner's manual, than none of us, including you, would modify in any way, shape, or form.

Carry on good people. 

BPD, I don't disagree with you.

I've thought long and hard about a staggered setup on my car, now that I have a cooled PTU I've been thinking about it even more.

That does not change the fact that Ford can and is denying warranty on PTUs and it can be as simple as very uneven tirewear.

My point is that folks under warranty may have some issues if they have a failure of their PTU with a staggered setup, they may face push back from Ford as that is happening at the dealership level.

[sunwolf]

Ford will typically only have an issue when dealing with mismatched sizes and AWD.

That can and does cause AWD components to fail.

Although I have been far out of warranty, I wouldn't necessarily agree with the blanket statement of mismatched tires causing AWD component failure.

After all, I've been a running example of not only different tire sizes from factory specs, but also have been running a staggered set, all without any issues whatsoever, for several years now.

Both DD use, as well as track tortured.

So I think that's kind of a premature statement/opinion to haphazardly throw out there for public consumption.

That is not an opinion.

I sleep with a master certified service adviser who has also spent some time working in the warranty department.

This is a real issue that can and does damage the AWD system. I can also assure you if you have a PTU failure with this setup under warranty, you should be prepared to pay for a PTU.

"Major dissimilar tire sizes between the front and rear axles could cause the AWD system to stop functioning and default to front wheel drive or damage the AWD system.

That quote is from my owners manual.

So which is the haphazard opinion?

[bpd1151]

Correct FoMoCoSHO.....

Which is why I stated from the onset, that I am (& have been) for some time, out of warranty.

Dealer's, &/or FMC, could theoretically deny warranty work for anything really.

I mean hell, if one puts a CAI on, they could theoretically deny warranty work for A., B., or C.

But in reality, one running simple different size tires alone (as stated by OP in this thread) isn't going to cause damage to the AWD &/or PTU components.

Which, is kind of what you eluded to. Which, as again I originally stated, not true.

I have been, & continue to be, proof of that, on the extreme end of the spectrum at that.

No intention of being argumentative either, just pointing out that the stated claims (of failure, perceived or otherwise) are incorrect.

One who chooses to modify, understands this precarious dance we play with FMC, just like any other MFG'er.

Just kind of is what it is, that's all.

[SHOdded]

Putting aside for a moment all the "generalized" considerations for different sized tires on the same vehicle, here is the TacomaWorld tire size evaluation for bpd's setup:

Only 1.3% difference, well within the 3% allowable variance.

Sure, rotation isn't possible, so keep a close eye on tire wear, tire pressure, alignment, etc to maximize life of tires.  Other than that, I don't see an issue.  Now if you are doing Funny Car setups with AWD, well ...

[AJP turbo]

I think because of the clutch packs in the rear diff is what makes running a staggered setup possible...if it was a full time awd system I would not try running a staggered size setup....not saying it wouldn't work but I wouldn't do it

Bpd I think you are just a beneficiary of this particular system.

If there isn't something to disengage where would the difference in speed between tires come from?...tire wear, gear wear,axle stress?...kinda like why for street use we need limited slip diffs and open diffs....if u ran lockers the tires bark and hobble...

It's never bad advice to say staggered set up on awd is risky unless car incorporated that from the factory.

I was never bold enough to try

[DakotaSHO]

Glad I came across this thread, was going to have new 245/45/20's put on today, called the tire shop up and got a price quote for the same tires only in 255/45/20's and saved myself $50

[sunwolf]

I now have 255/45/20 all around and with the speedometer at 75 my GPS speed was 77.5. OBDII speed was ~74.5. If you upgrade your tires you can always have your tuner adjust your tune for the larger size.