Have you thought of using a tire size that was specififed by the manufacturer? As for tread PATTERN you did not tell us anything about "the landfill". Is it muddy, iced up, rocky, and if so, how big are the rocks?

Depending on the road surface most of your travel is over, tire people will be able to recommend the correct tread pattern for that.

If I may interject my own personal prejudice....I personally am not convinced big "aggressive tread" tires accomplish much for the kind of ordinary off-roading I do. In winter, I seem to get along fine with ordinary "street tread pattern" tires - some of my neighbors out here in undeveloped ranch country go in for the "big macho" tires...but dont seem to have any advantage on our unimproved roads...as the mud...the ice..and the snow quickly clogs up their tire treads...leaving them "in the same boat" with me (which explains why ALL of us have four-wheel drive...and MOST of us have some form or variation of "locker" type rear axles, which, when combined with "dualies"....keep us going).

For ordinary highway travel at highway speeds, my personal prejudice is the big "knobby/aggressive/macho" tires are actually potentially dangerous.

As for tire size, I do not think it wise to try and improve on the design critera that went into your truck.

Without going into complex technical details, increasing the tire SIZE can have a potentially dangerous effect both on the truck's handling, and on the stresses imposed on its suspension.

As for towing, like you I use my truck for towing - both of my trailers, when loaded, weigh about 11,000. lbs.

I believe a "street" tread pattern ( meanng not aggressive like "knobby's, etc.) is best for towing. Here's why...towing imposes loads on the truck's whee....oops...RIMS that are best transferred to the road surface by a "street" tread. Has to do with what engineers call the "co-efficient of friction". Or, more simply put, the more rubber you have contacting the typical paved road surface, the more stable your truck wlll be.

 

I believe a "street" tread pattern ( meanng not aggressive like "knobby's, etc.) is best for towing. Here's why...towing imposes loads on the truck's whee....oops...RIMS that are best transferred to the road surface by a "street" tread. Has to do with what engineers call the "co-efficient of friction". Or, more simply put, the more rubber you have contacting the typical paved road surface, the more stable your truck wlll be.

It's a coefficient. Not hyphenated. And coefficients of friction have nothing to do with the "amount of rubber" (i.e., the area of the contact patch between the tire and the driving surface). They are intrinsic properties of material interfaces; the "amount of rubber" is an extrinsic property.

I don't dispute your point that on-road handling is better with on-road tires, but please, let's cut the quasi-scientific bullshit. We will all be much better off.

@Carryperez, your towing experience will get worse with larger tires because the truck has to put out more torque to generate the same amount of power, so the entire driveline will be under more stress and it'll tend to "lug" more. If you're okay with that, then drive on. Normally the way to deal with this is to regear the differentials but in L5Ps regearing is a Pandora's box of nightmares. Consider yourself warned.

 

6686?? Really? Guess we should never vary anything from factory. I runs 20” wheels with 265/60/20 Terra Grapplers up and down the AlCan pulling a 48’ enclosed gooseneck. I’ve had over 31k lbs GCVW on my 20’s on our roads. I put 81k miles on my last set of Nittos, split between towing and daily driving. If specialty tires didn’t work, Blizzaks and Ipikes wouldn‘t sell like hot cakes for dealing with ice and snow here in Alaska. Drag radials wouldn’t be worth a damn on my race Mustang, the factory engineers surely know the best how to make one hook up.

Carry, not sure on the biggest tire on the factory wheels, but the wheel width and lack of spacing between them really limits the options. You might be able to squeeze a 265/70/17 on the 17x6.5 wheels, but you’ll probably need a spacer between the rears. Something like the Terra Grappler or a similar AT tire will hold up to rocks and gravel really well. A more mud type tire will get chunks taken out of the lugs quickly and start coming apart. Highway tires won’t give you the traction in gravel and off-road. Every tire has trade-offs, pick what you need the tire most for and just make sure you can live with what it’s worst at.

 

6686?? Really? Guess we should never vary anything from factory...........

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You must be confusing me with someone else. I have made several changes to my Duramax to better meet my needs (some of which, for obvious reasons, I am forbidden to discuss openly in here... and for good reason......hint...move the letters "P" and "A" and "E" around ...!).

Elsewhere I have discussed what I did to ours to make it ride better. Elsewhere I discussed what I did regarding the lack of cabin air filtration in SOME years of our trucks.

As for the rest of your above post...we are not all that far apart. I most certainly agree with the "warning" to the OP!

 

Nope, the wheels have the backspacing built in to run 12.5’s with no spacers. The rear wheels do stick out of the fenders about 2”, but I live with it. I live in Alaska and run the AlCan regularly so I went with just a stock 3/4 ton size tire so I can find replacements anywhere. I have a ton of room between the duals with my skinny tires.