Which size tire

[partsman]

Bought a 2003 gmc 2500 HD used and now tires have had it, they call for 245/75/16 but owner put 265/75/16 on it, should I go back to stock size or go with the size he put on?

[CaberTosser]

Unless you have a need for the wider footprint & slight diameter increase then the stock size is probably best. Your speedometer will also be accurate again. Wider is better for soft terrain/ mud but worse for snow and ice, which do you realistically encounter more of?

[Big Grey Wolf]

Bigger the tires, less $$$ in your wallet!

[tirebob]

Both are common to see on those trucks. If you like the look and little bit of extra height the 265's do work fine but as mentioned above, narrower is a little better in deeper snow etc and with the factory size all your calibrations for speed, mileage etc are more accurate. Tires costs are a little bit cheaper in the OEM size as well although there isn't huge differences between them. Really depends on what you like better. I found going bigger to be more of a trade off for day to day driving than it was worth, but if you use your truck in ways the bigger is more helpful or simply more aesthetically appealing then it isn't enough of a jump to cause anything catastrophic to the usability.

[lannie]

The 265 size tire should give you a small increase in fuel milage but a small decrease in torque.

[CaberTosser]

Originally Posted by lannie

The 265 size tire should give you a small increase in fuel milage but a small decrease in torque.

Not really for the fuel mileage, though it is slightly taller and you'll travel slightly further per revolution that also comes with some physics trade-offs, one being that it will weigh more and take more energy to spin up, second is that the additional width has to displace a greater amount of air out of its way, this too takes energy. Lastly there is rolling resistance, more contact patch means greater rolling resistance. You’re correct about the ever so slight torque decrease though. Then with the added weight and additional diameter come negative hits to braking performance. With tires, absolutely everything is a physics trade-off. Note that anytime you see a vehicle designed to set fuel economy records, they invariably have super-narrow tires, almost like a long distance road racing bicycle (itself another example of tires selected for a purpose).

[gmcmax05]

Originally Posted by partsman

Bought a 2003 gmc 2500 HD used and now tires have had it, they call for 245/75/16 but owner put 265/75/16 on it, should I go back to stock size or go with the size he put on?

I owned half a dozen of these trucks that came with the 245's, first thing I did was put 265's on. They are only .75" wider & an 1" taller. You will not notice any difference in anything that is measurable, & you will have a tire with a larger load limit.

[Oldan Grumpi]

I went the other way, to 235/85 10 ply Hankooks. Much better all-season traction and a bit more clearance. I run them harder too, at 55 psi. (They're good for 90 pounds.) Having the computer reset to the tire size is a 2 minute effort at your favourite dealer. It's also the only way I could ever improve the mileage out of a 6 litre with slow diffs.

I always have the feeling that wide tires reduce the ground pressure too much (per square inch) and feel slippery.

One thing I can say for sure, I'l never again buy anything less than a 10 ply tire!

[CaberTosser]

Originally Posted by Oldan Grumpi

I went the other way, to 235/85 10 ply Hankooks. Much better all-season traction and a bit more clearance. I run them harder too, at 55 psi. (They're good for 90 pounds.) Having the computer reset to the tire size is a 2 minute effort at your favourite dealer. It's also the only way I could ever improve the mileage out of a 6 litre with slow diffs.

I always have the feeling that wide tires reduce the ground pressure too much (per square inch) and feel slippery.

One thing I can say for sure, I'l never again buy anything less than a 10 ply tire!

I also like a tall & narrow tire for winter, I wish there were some more options as I have a new vehicle that I'd like a slightly taller tire for but my dually rears and the lack of aftermarket wheel options (Mercedes Sprinter) make for very few available size choices. I'd like a 95 or 100 series sidewall option!

[Dean2]

Another vote for the 235/85/16 tires. 1" taller than stock, lower rpm at same road speed, more clearance with no modifications needed, fit on stock rim, better traction on ice and snow and less rolling resistance. Unless you go to REALLY wide tires you are not going to make a modern pickup float in sandy or swampy country. You need a light rig and at least 25" balloon type or Agricultural tires to get any flotation.

[Ice Fishing Maniac]

IMO, stay with the 265's for a bit more height.

[partsman]

Thanks for the info, it has the 6.0 litre gas with 4:10 and the 4l80e trans, I drive it in town to work and back and summer for pulling a fifth wheel.

[Puma]

I run 285/75/R16 studded Duratracs on my 04 K2500HD for the winter. This gives me almost 2" frame height gain from the stock tires.

Stock rims.

Speed difference from the speedo to my GPS is minimal. +2.43 @ 65 mph

[Tactical Lever]

Originally Posted by partsman

Thanks for the info, it has the 6.0 litre gas with 4:10 and the 4l80e trans, I drive it in town to work and back and summer for pulling a fifth wheel.

I'd go to a 305-75 if they fit! You definitely have the torque and the gearing.

It would bring down your rpm about 11%, which would offset the very slight increase in rolling resistance. Probably a net gain in mileage even going up to the big tires I suggested.

Also a smoother rough road ride, as the tires will tend to absorb the smaller bumps better.

[sledn]

235/85-16 Better mileage, better winter traction and cheaper. I have changed to these on work and play vehicles for the past 20 years.

[Puma]

Originally Posted by Puma

I run 285/75/R16 studded Duratracs on my 04 K2500HD for the winter. This gives me almost 2" frame height gain from the stock tires.

Stock rims.

Speed difference from the speedo to my GPS is minimal. +2.43 @ 65 mph

Oops 235 85 R 16 I had a brain fart !

[sako1]

Originally Posted by gmcmax05

i owned half a dozen of these trucks that came with the 245's, first thing i did was put 265's on. They are only .75" wider & an 1" taller. You will not notice any difference in anything that is measurable, & you will have a tire with a larger load limit.

exactly

[jstubbs]

I had two 2006 Chevrolet HD trucks, albeit they were diesels, but both were stock, with the only differences being one was an extended cab and the other a crew cab.

I had 285/75R16 Goodyear Duratracs on the extended cab. Mileage in town was around 12~ and highway was 17 mpg.

I had 235/75R16 (I believe, whatever stock size was) Michelin LTX M/S on the crew cab. Mileage around town was 14 and highway was 21 mpg.

Not sure how much is attributed to difference in tread and not tire size, but something to think about.

If I were you, I'd just stick with the tires on it, and when it came time, replace them with stock size.

[partsman]

Tried a comparison site and it advises against a 3% change

[tirebob]

Originally Posted by partsman

Tried a comparison site and it advises against a 3% change

Tire comparison sites are a source of data but are maybe not your best source of advice. Advising against going outside 3% variance is the correct standard advice if you want everything to remain as it is in comparison to stock, but that doesn't mean you can't 100% acceptably play outside that range as long as your are doing it for a specific reason, and the change is helping you make that reason work better, for example increased ground clearance, increasing load capacity, cosmetic appeal, etc...

It comes down to assessing what you are using your vehicle for, your personal preferences, and what you are will to give up a little to improve the areas most important to you. For that you need to ask the right questions and get the right answers.

[Dean2]

Originally Posted by tirebob

Tire comparison sites are a source of data but are maybe not your best source of advice. Advising against going outside 3% variance is the correct standard advice if you want everything to remain as it is in comparison to stock, but that doesn't mean you can't 100% acceptably play outside that range as long as your are doing it for a specific reason, and the change is helping you make that reason work better, for example increased ground clearance, increasing load capacity, cosmetic appeal, etc...

It comes down to assessing what you are using your vehicle for, your personal preferences, and what you are will to give up a little to improve the areas most important to you. For that you need to ask the right questions and get the right answers.

Spot on. Advice from someone like Bob or others on here who have used many different tires and aren't fan boys that think the one I have is the best, is a far better place to get info than the generic sites. These sites are lawyer proofed and don't represent a balanced perspective.