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285's on a Diesel Sub?
- Thread starter steelydan
- Start date
Don't know if clearance on my truck has any relation to the one on yours but mine rolled on 285 75 16 when I got it with no issues. Don't know the bakspacing of the rims and such though, and I suspect it might have been "cranked" before I got it..?
qwomack
JP5 Junkie
I am actually contemplating running 285's for my next tire to tame my 4.10's a little bit. I have cranked my bars and got about 3" of lift in the front.
Matt Bachand
Depends on the 6.5
Are you going to space your DRW or you think they will be ok w/out? I'd like to tame my 4.10's a tad also. DOn't have money for 6 new tires (to accomadate change) and the spacers...
qwomack
JP5 Junkie
No, I'll definitely put spacers on. My 245's are a little too close right now. The 285's will be touching, without a doubt.
steelydan
New Member
I had one 285 mounted on my Suburban for a test fit...fronts rubbed near the bumper rears were ok. Went with 265 BFG all terrain which are apparently the tallest 265 you can get. According to my tire guy all 265's are not the same height. Absolutely love the tires. Excellent in the snow. Passed several guys stuck while taking my kids snowboarding a week or so ago.
buddy
Active Member
Not all of any tire width is the same size/height. The ratio of the wall height to width is the second number. So 265/75 16 would be 265 divided by 25.4 to convert mm to inches, then multiply by the percentage which is 0.75. you have to multiply that by two for the wall above the rim and the tire wall below the rim. Then add the rim height to get your tire height. Basically, the higher the second number the taller the tire is for the same width.
Now some manufacturers have different tread height which make them a little different.
I had 235/75 15 stock, so should be 28.8" tall and when I bought the truck the tires were so old and balding that they were only 27" tall when not even on the truck weighted down. I have upgraded to 245/75 17 = 31.5" with aluminum wheels and it looks a lot better.
The aluminum wheels are soooo much lighter than the stock wheels, its crazy how much unsprung weight you could save by getting aftermarket.
I'd have run 235/85 16 if I could have found some skinny 16" wheels, becuase you have to find Rims 6-7" wide, and most are 8" wide. I came across the aluminum 17" at a junk yard for cheap. Seems hard to find the GM 5 bolt pattern too.
If getting 285s seems like youd want to get some wheels with a negative offset to get them away from the frame. Stock I think we have 0 offset if looking for aftermarket, but can live with like 15mm offset, negative if getting real wide tires.
I was going for fuel savings, so tall and skinny. The taller it is the lower the RPMs at cruise will be. the wider it is the more rolling resistance. If you get tall tires just know that your acceleration will get hurt, since it effectively increases your gear ratio. So if you had 3.73 with stock 245/75 16 and got 285/75 16 you now have a final effective ratio of 3.47. Which might help fuel economy on the interstate, but you probably negated it all by lifting it higher in the air, increasing the load needed to move the truck.
I'm actually looking to lower my front end now that it sits a little higher with taller tires, to make it a little more aerodynamic.
Now some manufacturers have different tread height which make them a little different.
I had 235/75 15 stock, so should be 28.8" tall and when I bought the truck the tires were so old and balding that they were only 27" tall when not even on the truck weighted down. I have upgraded to 245/75 17 = 31.5" with aluminum wheels and it looks a lot better.
The aluminum wheels are soooo much lighter than the stock wheels, its crazy how much unsprung weight you could save by getting aftermarket.
I'd have run 235/85 16 if I could have found some skinny 16" wheels, becuase you have to find Rims 6-7" wide, and most are 8" wide. I came across the aluminum 17" at a junk yard for cheap. Seems hard to find the GM 5 bolt pattern too.
If getting 285s seems like youd want to get some wheels with a negative offset to get them away from the frame. Stock I think we have 0 offset if looking for aftermarket, but can live with like 15mm offset, negative if getting real wide tires.
I was going for fuel savings, so tall and skinny. The taller it is the lower the RPMs at cruise will be. the wider it is the more rolling resistance. If you get tall tires just know that your acceleration will get hurt, since it effectively increases your gear ratio. So if you had 3.73 with stock 245/75 16 and got 285/75 16 you now have a final effective ratio of 3.47. Which might help fuel economy on the interstate, but you probably negated it all by lifting it higher in the air, increasing the load needed to move the truck.
I'm actually looking to lower my front end now that it sits a little higher with taller tires, to make it a little more aerodynamic.
Last edited:
Paveltolz
Доверяй, но проверяй
Buddy of mine added 285s to his K1500 Tahoe and carved holes in the front fenderwells from rubbing in tight corners.
FWIW - I backed my T-Bars down after having to replace the ball joints ($1100):mad2: (PO turned them up and that repair was way outside my expertise). Then did the lift "right" and added the 285s later. I was told by the folks that did the lift that turning up the bars would translate to more rapid wear and tear on ball joints. Speedometer is acurate now too.
FWIW - I backed my T-Bars down after having to replace the ball joints ($1100):mad2: (PO turned them up and that repair was way outside my expertise). Then did the lift "right" and added the 285s later. I was told by the folks that did the lift that turning up the bars would translate to more rapid wear and tear on ball joints. Speedometer is acurate now too.
Matt Bachand
Depends on the 6.5
CV's actually were relatively cheap, don't think you'll bring those out of range. Go too high, and you will be out of range for an alignment which is a MUST on anything besides a dedicated plow truck. I would match turn for turn, measure an inch then try the other side.
I'm scared to touch em to be honest. My truck is low with the plow, but it works fine. I've seen broken torsion bars, and thats the last thing I want tto deal with when it wasn't broke to begin with. Then again, alot of people crank em no problem.
6.5 Rack body I plow with cranked his up, he has a ton more room in the wheel well now.
Its balljoints and tires if you're out of alignment are the biggest 2 things.
Matt Bachand
Depends on the 6.5
I bought 6 2 years ago and I went from 215 to 225's, they told me 235's would rub. I'm not sure if i'll ever buy 6 tires again at the same time, so I may be stuck with 225's.
qwomack
JP5 Junkie
I turned mine up all the way until they stopped, and backed the bolt off 3 even turns on both of them. The ride is a little stiffer but not unbearable. There's a picture in my album that shows the CV angles on mine and they are not that bad. On edit, it's the second picture in my album.
Matt Bachand
Depends on the 6.5
Hats off bro, that is one awesome truck you got.
qwomack
JP5 Junkie
Thanks, Matt. She has done me real good once I got all the kinks worked out. I plan on keeping her for a while.