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my 09 2500HD 2WD came with 16" wheels & all-season tires
from what i gather for whatever reason they all come like that from the factory
is there any advantage (besides monetary) to this?
i find they look kind of weird on that big truck, plus the tires tend to spin more than i was expecting on wet surfaces (gravel, grass, etc)
If you go with a bigger tire remember to compensate for the speedometer error. You'll actually be traveling faster than your speedometer says you are. If you have a GPS check your speed on the speedometer and GPS at say, 60 mph with the smaller tires. Then, when you install the larger tires drive the same speed on the GPS and see what the speedo says, there will be a difference.
From experience, I will tell you that changing the tire size will mess up your console information, if you cannot adjust you engine information. My console routinely told me that I used about 1-1.5 gallons of diesel less than I had to put in the tank when I refueled. Also overstated the mpg as compared to my 245-75R-16Es that were originally on the truck. When I bought new tires, I went back to the 245s from the 265s that I put on. Hopefully it won't turn out to be a big mistake. They do look a lot like doughnuts, don't they?
__________________ jal
2009 Crestliner Superhawk 1900
175 Optimax Pro SX
Dodge Ram 2500 HD Cummins Diesel
On the early year 2500's (like mine) they only came with 245-16's. Later models (I think this started in 2007 or 8) the Z-71 versions and some of the 4x4 versions came with 17" inch rims or even 265-16's. If they are now offering different size tires and wheels, then there is a (factory)way to adjust for it. Used to be the gear that goes in the trans for the speedo was interchangeable. So many teeth for tire size/ gear ratio. Probably a $15 part, but you need to get the right one. The 265-16's fill out the wheel well a WHOLE lot better than the 245's. There's also a few after market tuner "chips" out there that allow you to adjust the ECM program to account for tire size changes. You may even be able to get the dealer to adjust the math in the ECM. They wouldn't do that a few years ago when all that was offered was 245-16's.
Drastically changing the tire size without "letting the computer know" is very likely to also have a detremental effect on performance and mpg too as the computer relies on the speed signal to "make decisions" like shift points, fuel requirements, timing advance, etc.
my 08 duramax came with 16" alloy wheels and 245's. they really do look like donuts. i immediatly purchased a set of 285/75r16. it is the best tire size i think you can have for a stock truck.
FWIW, after I increased tire size I took my truck back to the dealer and they adjusted the ECM to the larger size at no cost to me. (Takes maybe 5 minutes)
Most trucks ECM's will accomodate tires to 285, but anything larger you'll need an aftermarket programer to adjust the computer.
GM has always been bad about putting small tires on their trucks especially the 2500HD. I would just go to 285s and keep the rims. I'm sure if you're worried about mph/odometer being off, your local dealer or other auto shop could fix that with the computer.
245's are put on at the factory so that they can get the hp and torque that they claim. That being said I put a set of H2 rims with 285/70/17 BFG's on my 2500 duramax
If you really plan on doing some towing you may want to consider that when you change the diameter of the tires, you are also changing your gearing. Your 3.73 rear end (guessing) with those 245s effectively becomes a 3.60 with 265s. If you go to 285s, then you are talking a ~3.47 gear.
Depending upon how you want to use the truck that may make a considerable difference in how the vehicle really performs, even after you get it reprogrammed for the new tires.
Here is a link to a calculator to run some of those numbers if you are interested. Here is another link that will show you how much your speedo will be off and various other tidbits.
I agree those 245s look way too small for the truck. That's what they have been putting on for quite some time. They spin for a reason though; you have max mechanical advantage with the gearing and the smaller tires. If you put bigger ones on and they will be wider, which helps with traction, but you lose some of that mechanical advantage.
I went up just one size on mine, from 245s to 265s and I think that is a good compromise. Lots of people run 285s with no issues. I think you can run 305s with maybe only a tiny amount of rubbing at a full lock turn with some suspension flexing. If you were going to really use the truck though, I would change gears before jumping up that much in tire size (305)s.
__________________ There is nothing - absolutely nothing - half so much worth doing as simply messing about in boats
long board thats good info...thank you very much for the input
i think i will take your advice and consider 265's
when i do tow (20x ish a year) its a 250 mile round trip
Im went to 285/75 16 terra grapplers on my 04 Suburban 2500 4x4. The do rub a bit at full lock when in reverse but thats no big deal and could proably be resolved by cranking the tortion bars a bit more.
While I knew I would be messing with the gear ratio, that was kind of what I wanted to do besides make it look better. My truck has the 8 liter gas engine and its a pig. An 8 mile to the gallon pig on the freeways (the way I drive) without boat in tow! My intention was to reduce my RPM's at highway speeds and increase my efficiency by going to larger tires. It did take away some of the power off the line with the boat attached but that isnt a big deal. I always put the pig into 4 wheel drive on the ramp regardless as our ramps are steep and slick.
The dealer can definately fix the speedo issue. According to my dealer, there are already provisions in the ECM for that tire size so its a simple fix for them.
I have a 2005 3/4 ton Chevy 2500HD 4x4 and went with the 285's and they rubbed on tight turns so I went to the guy that does my realignments and had him tighten the torsion bars just a little so they didn't rub but you will have to get it realigned and that was no problem. It did make it ride a little stiffer though
wheels and tires...2500HD 
