New 20" Nitto Crosstek's installed - spec's

[CaptnKirk]

Gents:

I just received my OEM '08 8-spoke wheels and went to NTB for Nitto Dura Grapplers after trolling the forum here and toiling for some time over the decision. Somehow I walked out $1500 later with 4 new Crosstek's. I need to verify what they told me about the size and thought maybe someone here could validate the info as well as provide some other answers/knowledge.
They told me the 2006 - 2008 OEM size/aspect ratio is 275/65R20 but the sidewall height looks taller than I recall on trucks that have the 20's on them already. Can any of you out there confirm if that is in fact the OEM size?
Also, I drove in on OEM 17" 5-spoke wheels with the Michelin LTX A/T 2 and I am now noticing alot more "shudder" from the truck over pavement irregularities. Is this normal when going to a 20" wheel tire combo in contrast to the 17" combo? I'm running 65 psi - fyi.

[I'm broke]

They are correct about the size. I bought an '11 with the 17" wheel due to having the '08 20" wheels in my garage I was running on my '04. The 275/65-20 is what has been coming on them stock since they started running 20's from the factory. As far as the shuttering...I can't answer that very good. The 20" size should play no part in that whatsoever!!!!! The only things I can think of is the tread pattern, which I don't know what that is on the new tires you bought could be a very different ride than the stockers that were very smooth. More aggressive could mean a little rougher. Or there could be a balancing issue with the new tires. I did run a set of firestone MT's that were a straight aggressive mud tire and they were supper smooth. My 2 cents is that the tires are out of balance or the rims could have something wrong with them. Also double check your lug nuts to all be tight.

[CaptnKirk]

Anyone have any other thoughts on ride differences expected when going from 17" to 20" OEM tire sizes?

[CaptnKirk]

I didn't get a lot of response from anyone, but I do know in talking with several members that I am not the only one trying to remove this issue in my front end.

FWIW................

I added OEM 20's with OEM tire sizes and the front end felt less stable. Went back to NTB and they checked the front end, said all is well. Went to dealer #1, they said the same thing. Both admitted they could feel the issue in the steering. Went back to NTB, removed the Crosstek's on the front and installed Michelin LTX A/T 2, problem actaully worse. Went to dealer #2 - they couldn't "feel" the issue and said front end was in great shape.

Then drove around trying to convince myself that I am an OCD case and that the average person wouldn't notice the issue. Realized I am not average person.

Went to dealer #3 - BUT - this is a Ford dealer that does not sell cars and only sells the SD and bigger up to and including OTR tractors. Forty minutes in the stall and I see them back it out. Walk up to service advisor ready to depart with commentary along the lines of the prior three efforts. Here's what they told me.

OEM says you have to dissassemble the ball joints to check them. One was bad, one was loose. Front tie bar bad, drag link rod assy bad, drag link rod end asy bad, steering gearbox out of adjustment. I asked why the others didn't catch this and this is the point of my rant - they said the average dealer is not able to truly load stress the front end of the SD suspension enough to actually take it to limits that expose front end parts that are exceeding OEM specifications. They said this is also why so many report death wobble yet "seemingly" can't find anything wrong.

So, I get in after a quick $100 check - gremlin not gone...all the way. Still there but not as bad. Thinking about pulling my hair out. I start thinking about a new GM product and about a 2011 SD. Two days later, I get a hair in my a** and I adjust my brand new Rancho RS 9000 9-way adjustable shocks up to their max stiffness just for sh**'s and gigglles and wait for it..........gremlin totally gone.

Go figure. I did the 9000's to begin with and never would have gone back to them if I wasn't sitting at my son's baseball practice passing time. Who'd a thunk?????