Not planning on it any time soon, but was thinking of going up a size or two for tires. I wish GM would start with larger tires like everybody else. Other than the speedo being off and it having a negative effect on towing any other issues?

shift points....too big is hard on suspension

I'm not looking for huge tires probably 265 or 275's.

you'll be fine

No problems

mine came stock with 265's so you should be fine.

I'm on 265's Nokians for the winter (from 245's) no probs. Probably will replace stock 245's in the spring for same size of 285's.........shouldn't be any issues.

Not planning on it any time soon, but was thinking of going up a size or two for tires. I wish GM would start with larger tires like everybody else. Other than the speedo being off and it having a negative effect on towing any other issues?

Size I am running with stock heigth suspension:
275/65R-18 (32.1" dia)


ReadyLift says max size with level lift:
285/65-18 (32.6" dia)

Stock ref:
245/75-16 (30.5" dia)
265/70-17 (31.6" dia)

So my 275/65 18's are only a half inch in diameter larger than the 17" stock tires anyway - get a few miles of wear on them and they will be the same diameter LOL. But 1.6" larger in diameter than the puny 16's the truck came with.

:cool:

Just replaced my 265/75/16 BFG's with the 285's. My rims are aftermarket, so they are a bit wider. the 285 BFG's have a diameter of 32.8, and no codes issues yet, knock on wood. I still need to check and possibly recalibrate the speedo since I gained 2.3 inches.

You will need to level and trim to fit 285's on a non stock rim. I was touching metal.

[quote=azcamp305;2343006]Just replaced my 265/75/16 BFG's with the 285's. I still need to check and possibly recalibrate the speedo since I gained 2.3 inches.

Isn't going from 265/16 to 285/16 just add about 1-inch in overall diameter? Why do you say 2.3 inches?

http://www.miata.net/garage/tirecalc.html

Actually 265/75/16 are 31.6" dia. 285/75-16 are 32.8" in dia.

But I do believe you would have had 245/75-16 stock that are 30.5" dia.

Gain of 2.3" in dia and 1.15" in ride heigth.

See the tire calculator link above, very handy - tells you percentage to add to your speedo. In this case add 3.7% for true speed and odometer readings.

:)

DaveRuane, you're right, 265 to 285 is 1-inch. I forgot to mention that my truck came stock with the 245's, so I was comparing from those to the 285's.

Jimmy, cool site for tire calculations....looks like I will definately need to readjust my speedo. 245 to 285 is a 7.8% difference. thx

I run 285/75/16 on the stock rims ('07.5 2500 4x4) and the only issue is light rubbing on the bottom rear edge of the plastic mud guards in the wells. It only happens when I turn all the way and usually only the outside tire when the suspension is loaded from turning at speed. It's no big deal, but if anybody's got an easy fix, I'm all ears.

I run 285/75/16 on the stock rims ('07.5 2500 4x4) and the only issue is light rubbing on the bottom rear edge of the plastic mud guards in the wells. It only happens when I turn all the way and usually only the outside tire when the suspension is loaded from turning at speed. It's no big deal, but if anybody's got an easy fix, I'm all ears.


Level lift.

i got 305's with a leveling kit, no problems except for some trimming

Jimmmy, can you explain? I am new to both diesels and anything bigger than half tons... My older half ton Z's never had problems and my last truck was leveled before I bought it. How does it work, what does it cost, and the biggy - will it void the warranty on the first brand new truck i've ever paid for? Big thanks.

The front torsion bars can be turned up - or there are kits that get it done and supposedly don't affect the ride. Search for Ready Lift and Cognito kits. Yes mods can possibly cause warranty problems - if the mod caused the problem. Doesn't stop most from changing things - I went bigger tires - just don't want any lift on my rig - like the ride I have.

:)

durasoldier,
As Jimmy says, you can just turn up the Tbars by an inch, and still be within factory guidelines.

But you really need to get it realigned after adjusting Tbars . . . so best case, take it to a tire shop and have them turn up the Tbars. Test drive to see that your rubbing is solved, then have them align it. You prolly need a leveling kit to go up by 2 inches, but the LMMs are good for lifting by 1.5", just as factory issued. In fact, as long as you're not rubbing the undercurled fender point, you might not need to lift at all. Just pull back the wheelhouse liners using a zip-tie.

I run 265/75/16 on my 01 have noticed no difference

I did the leveling kit on my '08. The dealer did it, and they changed out the torsion keys, so you get the lift without the increased tension and rougher ride, the kit also included the longer Bilstein chrome shocks and front end alignment.
I did have to cut that metal piece in the fender well against the cab. I just zip tied the plastic and now There is NO rubbing at all.

Thanks for the info JIMMY and HOD... sorry for the delay. Good to know, i'll try the zip ties first as the rubbing is very minimal. I did lose one of the plastic retaining caps that hold the fender in place though. Bottom rear on the right side got clipped off by the tire rub. No damage to the fender, but just enough to grab the top of that cap and pop it out. again, 285/75/16 and they are Durango Radial XTR for those that care... used to run BFG All Terrain KO, but these were about half the price, still had the 50,000 mile warranty and have performed just as well off road. They make slightly more highway noise, but I think they have worn more slowly on pavement than the BFG's though. Anyway, thanks again.

I did the leveling kit on my '08. The dealer did it, and they changed out the torsion keys, so you get the lift without the increased tension and rougher ride, the kit also included the longer Bilstein chrome shocks and front end alignment.
I did have to cut that metal piece in the fender well against the cab. I just zip tied the plastic and now There is NO rubbing at all.


This is a common misconception and the way they advertise aftermarket keys like Ready Lift. Anytime you increase the ride heigth this way - you do so by cranking to torsion bars with or without different keys.

This limits suspension travel - so you will hit the stops sooner for a rougher ride. ;)

My understanding is the different keys allow for the lift without having to crank the torsion bars as much. Otherwise, why change the keys at all? I will say that I gained about 3 inches in height with this kit, whereas my '01 duramax was cranked with no key change and I got 2 inches and a stiff ride. The kit was worth the money in my opinion.