2kwik4u

Thanks for the info on the shocks. I can't remember the tire size on the Yukon. They were stock size as best as I can tell. I also moved to a 17in rim from a 16in rim at the same time. That might also have contributed to the increased stiffness, hadn't thought about that until now. I'll have to check the axle ratings and the tire ratings to see where I land on a set of P tires. I do very little off-roading around sharp rocks. Lots of gravel and mud trails around a friends farm, and then the wet boat ramps dictated the 4wd.

Got a link to it? I can't find them anywhere on amazon as a set. Especially for that price.

Sounds like the 5100's are the way to go. Would I just leave them on the lowest setting, or is there a "middle setting" that results in no lift/drop? My biggest complaint with the Ranchos is the "bounce" after the hit. Most noticeable on sharp edged bumps like expansion joints and things like that. It's almost as if there is NO rebound damping, and only bound damping. Hit the bump and there is a noticeable procession after the initial hit. Feels like there are 3-4 more oscillations in the suspension before it comes to rest. The low shaft speed damping seems OK as the truck doesn't float or bounce excessively, but the high shaft speed damping is off and makes the truck to stiff overall. With any luck the 5100's will cure some of that. I'm nervous on going to a P tire as I tow a LOT in the summer. 2 trips a week on average to the lake with a 5,200lb boat, 4 people, coolers, etc. Don't want to get a set of tires that tow "squishy". Had P tires on my '03 Yukon, swapped to LT tires and the towing got much better immediately.......I'll go read some other threads on that though

Thanks for the info. Most likely will go with 275/55/20's again on the next set so I don't have to monkey with the speedometer and being off (even your suggested sizes aren't off by much). I've had my eyes on the Continental A/T tires. I run Continentals on everything else I own with wheels (including the Cannondale, excluding the lawn mower), and like them. The BFG's were on the truck when I bought it, and have been wearing well. Probably a year or two left in them at this point. I also run around with 200lbs of sand in the bed. 100lbs on each side behind the wheel well. Tried U-Bolts, clamps, and a few other things to get the 75mph shake to go away. Sand was the cheapest and easiest. Been considering having some steel plates cut at the shop to bolt to the frame back there so I don' t have so much sand in the bed, just haven't gotten around to it. Bought the truck when I was commuting 6 miles one way. Changed jobs and am now 28 miles one way with lots of interstate, and a fair amount of business travel thrown in as well. The highway shake, and super rough ride are getting old quick, but I love the truck otherwise.

OK, 120 pages into this thread and I've lost myself in all the details. Hoping I can get someone to confirm/deny a few things before I pull the trigger on a set of 5100 shocks. Getting ready to put new shocks on my 2015 GMC Sierra SLT w/Z71 package. Currently has the factory Rancho Shocks at about 63k miles. I'm also running BFG KO2's in a 275/55/20 size. This is the worst riding GM I've owned, beating out the somewhat lowered '06 Tralblazer SS I had, as well as the '00 S10 that you couldn't roll a coke can under the frame. I'm suspecting it's the stiff Rancho shocks, and the stiff KO2 tires. I'm not going to change tires until these wear out, so shocks are next on the list. I don't want to lift/level at all, but like the reviews of the 5100 shocks. Can someone confirm these part numbers for me to make sure I'm getting the right ones? Fronts = BILSTEIN 24238304 Rears = BILSTEIN 33238319 Also, I remember reading somewhere that there was a less expensive alternative to these if you didn't want a lift/level. I've lost that link or info somewhere along the way. Can anyone comment on an alternative Bilstein part number that will ride the same as the 5100's, but don' t have the height adjustment on them? Finally, can anyone recommend a reputable source to purchase from? Amazon appears to have them in intermittent stock, and Rock Auto only has a single of the fronts left in stock. Those are my two "go to" sources for online parts. Thanks in advance!

Saw this and immediately thought of this thread

Thanks for the info. Found that site already. Doesn't seem to work well on my phone. Next time I'm near a PC I'll try to give you some info on my truck. Any chance you can run my VIN through your database to see if the previous owner had found you as well. Was awfully suspicious that the truck was traded in with 35,875 miles on it

Just bought a 2015 GMC Sierra SLT 4-door/short bed/5.3/4wd/3.42/36k miles a few weeks ago. Was looking for info on vibrations at speed and stumbled into here. WOW, what a mess. Really like the truck with the exception of the highway vibration. During the test drive I attributed it to the brand new BFG AT's on the truck. Overall it's not an issue for like 90% of my driving as I typically stay below 70 commuting and towing. The other 10% that are a few yearly road trips will be an issue though. I've dug through about 100+ pages looking for the fix. I suppose that there just isn't one at this point? Seen a few guys say this that or the other thing has "fixed it", but no definitive "DO this, and it will work" solution. Plans are to have a Road Force Balance done. Then try a set of spring clamps to see if that helps. Any thoughts from the resident experts before I read the remaining 600 pages of this thread?