It all depends on the profile of the tire. Not the rim size.

For example using Goodyear Silent Armor tires the follow can be found

                   LT265/75R/16 = 31.7" in diameter   In load range E =3415 lbs load

And              LT 265/70R/17 = 31.7" in diameter  In load range E = 3195 lbs load

Two different rim size but the same diameter and same rolling distance around the tire.  so they would not change your gear ratio. To the engine and powertrain, They are one and the same.

But the tire on 16" rim has a taller aspect ratio  ( 75 vs 70) and will hold more air, giving it a higher load capacity.

So even though the energy to turn the two tires is the same ( same number of RPM per mile), the different size will equal a different load capacity. Which may be important to you hauling a gooseneck or 5th wheel.

Ford, GM and Dodge rate your tow capacity on the total power train gear ratio. ( Tire size & rear end axle ratio) If you are the same aspect ratio on two different size rims. Say  a 265/75r16 and a 265/75r/17 You would have a taller tire on the 17 rim and that would affect your final drive ratio and your towing capacity. This would also be true if you stayed with 16" rims and just went with a taller tire. 265/75/16 vs 285/75/16

I agree with the 2 replies above.

Are you looking to upgrade a truck you have or buying a truck with 17's?  If possible I would try and stay away from 17's, I know it is getting tough to do because everyone is going that direction.  But my Dodge has them and the 05 Dodge we had also had 17's and we had a hard time finding one with the correct weight rating.  With the 16's there is a large number of brands out that have a wide range of weight rating and the price is cheaper.

I'm going with 19.5's on our Dodge in March, unless I can find a bargin sooner.

I know this is going to mess with your mind, but.................

37.5X12.50X16.5 have a load capacity of over 4000 pounds.

I have a set on my 1986 4WD F350 6.9L 5spd ext. cab and love em.  I can go places with those bad boys in 2wd that I needed 4wd with regular tires.  They are a little heavy, but not too noisey and they wear like iron.  Plus they were a good deal compared to other big tires.

deranger

If all you want is a little bigger tire. Bump up to a

285/75R/16 at 32.8"    In a "D" load range =3305 lbs

295/75R/16 at 33.4"    In a  "D" load range =3415 lbs

They are pretty hard to find those sizes in "E" range tires. But the load limits for the "D" range are almost the same as the 265/75/16

The disadvantage is the recommended rim width bumps from a 7.5" rim to a 8" wide rim

My very limited experience has shown that when I squeezed a wider tire on the stock rim ( especially when I dropped from a "E" to a "D" load range) is that I got a little more squirm in the tread. It handled ok, but the tires wore faster than if I had the recommended size rim or stayed the heavier load range. "E" range tires run at 80psi and "D" range tires run at 65 psi. So even though they are rated for the same total lbs weight on the load, They just don't seem to be as stiff of a tire because of the lighter air pressure, which allows the squirm. 

One of the advantages of a bigger tire is that you increase the size of the contact patch with the road. A bigger patch = more traction.  The advantage of going taller vs wider is that you get a larger contact patch with the road with out more aquaplane in wet weather.  Too often when we buy a bigger tire, we get both taller and wider.  A wide tire has to push more water out of the way. A taller tire with a longer patch push the same amount of water out of the way as the smaller tire, but has a long contact patch for more traction.

Goodyear does make a 285/75r/16 E tire rated at 3750lbs this tire is 32.8" tall  it will fit on a 7.5" to 9.5" rim with an 8.0" being the preferred. So while the heavier load ratings in the bigger sizes are harder to find, they are available if you search around.  You will just have to search the various tire makers and see if they make a "PLUS" size tire for your truck in a load range you want.

D = 8 ply

E = 10 ply

You can't go wrong with the LR-E/10 ply tires.

On a 1 ton truck, I'd probably stay with 10 ply, especially if you hare hauling any kind of gooseneck where you are coming close to the load rating of your truck.

Bumper pull trailers don't put that much weight on your rear axle. So it's not as big of a deal there, unless you are hauling a camper or something else in the bed while you tow.

I agree with you hogtownboss, I put BFG's on our 2001 super duty and the tire dealer recommended we not use them.  He said the tread was too agressive and because of the extreme weight up front on the diesel super dutys that we would not get good wear out of the tires and they would wear prematurely.  I'm a little hard headed, so I had him put them on anyway.  I've been tickled with the performance, ride, handling and I've kept an eye on the tread wear to see if I need to rotate more often?  The tires are doing fine and I'm not getting that much difference in tread wear from front to back anyway.  Course, we don't hotrod or cowboy our super duty.

deranger

A couple of years ago after my Firestone debacle, I had BFGs "E" range installed on my truck. I've been very impressed with their taught feel, excellent tracking, quite running, good wear and they really do well in both mud and snow.

I've been using BFG exclusively on my cars for years. This is my first experience with their LT "E" tires, and this Spring I will be installing them on one of my trailers. I'm pleased with their performance and value.

Gard

5820 for the pair is correct...

The main reason that dual tire load limits are set at a lower rating than single tires is that tires paired up as duals do not always contact the road surface equally. Examples of this would be ruts in the road surface, climbing over curbs, mismatches in inflation pressure and/or remaining tread depth, to name a few.

This unequal road surface contact results in one of the dual tires ending up carrying more than its fair share of the load. In order to provide a “safety cushion” for when this happens, the maximum weight allowed is set lower than for a single application.

Interesting. 

Although lower rating, teamed up creates a higher rating.  Is that how the DWLy gets a higher payload capacity?

Then the 285/75/16 would be a good upgrade for you.  But that only gives you a 1" taller tire.  The 265 = 31.7" and the 285 =32.8" tall

The following are all available in "E" load range in the 285/75/16

Goodyear Wranger SR-A

Goodyear Wrangler Silent Armor

BF Goodrich All Terrain KO

BF Goodrich Mud Terrain T/A

Bridgestone Dueller A/T

Michelin LTX

Firestone Destination M/T

And you could look at the 295/75/16 That will give you another 1/2" in hieght, But you won't find an "E" range in that size.

BF Goodrich All Terrain T/A

General Grabber AT/2

Don't forget those taller tires changes your final drive ratio.... Larger diameter tires makes towing a little more difficult (get up and go kinda got up and went, and the hills seem a little taller), and may also bring a little sway into the picture... Jumping from a 31" tire to a 33" pretty much turns a 4.10 into a 3.73. Something to consider.

I agree.  The 2000 and 2003 Fords I have owned came with 265/75/16 and I replaced them with 285's when the original tires wore out.  No probems

My current 06 ford came with 18" wheels and I replaced the stock tires when they wore out with tires 2" taller. And I still pull the trailer just fine. And I go over a lot of 7000 to 8000 foot elevation mountain passes around here.