285/75/16 tires on a 2008 GMC Sierra 2500HD?

[Climber Rob]

Anybody running this size on their stock 2007+ 2500HD? I'd like to go as big as I can without any modifications or cranking the torsion bars. I ran them on my '03 2500HD without any issues. Seems like they will be really close on the front wheel well/bumper clearance, as the wheel wells appear a bit narrower than my '03. I'm aware of the mileage and speedometer impacts. Just wondering if they will fit without rubbing. Any input is appreciated!

 

[digitaldelay]

I would think a levelling kit or torsion bar adjustment would be required. Why not try an LT255/85R16? Same overall diameter and less rubbing issues.

Jason

 

[bob91yj]

I work at a GMC dealership, they will rub. There are factory torsion keys you can get to level the front, add the correct shocks an alignment and you're done. If interested I can get you the part number for the keys.

 

[Climber Rob]

Jason: Thanks. I used to run that size on my Toyota, but I like the wider footprint tires on the 3/4-ton in the sand and loose rock. I find the skinnier tires dig in too much on an already heavy truck with all of our gear loaded up. The heavier tires "float" more. Plus, not too many choices in the 255/85 these days.

Bob: Where do they rub? I don't mind a bit of trimming, if necessary. Seems like there's plenty of height in the wheel-wells, and that the bottom lip of the front bumper will be the issue. I'm thinking I'd prefer to go with some trimming and fender flares if necessary, rather than add keys and shocks.

 

[jeepn0811]

My friend has a 2010 4 door 2500 4x4. He used a leveling kit and runs that size no problem. It looks like he could actually go to 315's (34")

 

[bob91yj]

They can rub at the front and at the back of the fenderwell. Steering at/near full lock into/out of a driveway. Maybe you can cut/trim enough that you can adjust it out cranking the torsions a bit at the cost of ride quality.

Keys and shocks stand a chance of improving ride quality. I'm content with the RCD spec Bilstein 5100's currently on my truck. I did some service work on the Bilstein chase truck at my shop, I talked to Joel about the shocks on their truck, looked like a 5100 with a remote reservoir. Apparently they were testing a new shock line that they have coming. Hold out on the keys/shocks until the new shocks come out. I think you'll be happy with the outcome.

Apples and oranges but I've got a 6"RCD lift, running 315/75/16's on my '06, done some trimming and it still rubs when the tires are new (it's that close).

 

[Climber Rob]

Thanks Bob. I'm going to go with the new rims and tires and crank the bars with the stock keys a bit, then do a bit of trimming.

My shocks will need to be replaced soon, anyways, and I definitely will be installing Bilstein 5100s.

 

[Mark Harley]

Get new reindexed keys, don't crank the bars, This only starts problems.

 

[1stDeuce]

Fellas, cranking the bars is the same as putting in new keys. No difference AT ALL, excepting the amount of work involved. The ride benefit of a quality "leveling kit" is that it will include either longer shocks or taller lower shock mounts that allow a normal amount of droop travel to be retained. The old "Cranking the bars makes the ride stiff" was due to people cranking the bars and then having no droop travel left, such that the truck follows the tire down instead of just the tire/wheel dropping to follow the road.

You can buy the shock brackets separately these days and they're cheap. The stock keys are usually good for at least +1" of ride height, and usually closer to 1.5" or 2". I'd recommend brackets if you go past 1". I'm at 1" right now on my truck and it's OK, but I've gone from about 3.5" of droop to about 2.5". Any less and I'd probably not like it, and I'll probably toss a 3/8" spacer under the bracket soon to get 3/4" or so of droop back.

To look at it a different way, whether you crank the the bar or put in new keys, all you are doing is changing the angle that the static end of the bar is at, and whatever amount you change that angle by translates directly to the same angle change at the lower control arm, which makes the truck sit a little higher for the SAME EXACT amount of preload (twist) on the bar. You are not "adding twist" to the bar, or raising the spring rate, or anything like that. Keys are certainly necessary for larger amounts of lift or "levelling", but not necessary for subtle adjustments.

Lots written on this topic in the suspension section at dieselplace.

And to the OP, assuming stock wheels, you'll find that the driver's side tire will rub at the back of the wheel well on the plastic liner. Looking underneath, you'll see that it's pushed forward some by the parking brake cable routing. Get a HEAVY zip tie and tie the cable back some (this is the part that runs in a sheath, so no worries...) and it'll probably get rid of most of the rubbing at the back of the wheel opening. A hack saw/sawzall/whatever for a little bit of trimming of the fascia and you're good to go. If you put on wider wheels or wheels with less backspacing than stock the rubbing gets more severe.

Good luck!

PS, no matter how you do it, lifting the truck from OEM intended ride height WILL be the start of "problems".

 

[tombodad]

Not sure if this is a no-no, but here's a link to an informative thread:

 

[AA1PR]

here is a tire size calculator link for you

http://ejelta.com/tiresize/?ws17=1&

I also am getting the leveling kit for my 04 yukon, the leveling key only runa about $130, longer shocks and checking the toe alignment is a must afterwards also

my problem is finding a shop that has the lift capable to lift it & wiling to do the work

I was also told that if I go to say 265/75/17 it would throw the computer system off and cause problems, not sure if yoru truck would too, or if anyone knows for certain ?

 

[tombodad]

Remember though, that several manufacturers do not run true to size. Best source is from the manufacturer, or bust out the ol' tape measure.