Tire size difference

OP, what width are your stock wheels? Will they work with the wider tire?

As to the ACTUAL size of the tire, you need to find the manufacturer's published measurements as they can and do vary from the nominal listed size.

Do you have clearance up front ....turning radius for wider tires?

Higher load capacity is good. I hate having tires as the 'weak' link when towing/hauling

jimh425 wrote:
5 lbs of unsprung weigh isn't that bad. You could always upgrade your shocks. Keep in mind that many of us switched to 19.5s on SRWs which are way heavier.

For the record, my current truck a F450 came with 19.5s.

Already put Rancho 9000XL shocks on the rear as that is what my last truck (Ford F350) had and fronts will be replaced soon.

Steve_in_29 wrote:

As to the ACTUAL size of the tire, you need to find the manufacturer's published measurements as they can and do vary from the nominal listed size.

Bingo! Actual tire dimensions - for a given size - vary widely from one brand/model to another. And they also vary depending on the wheel width they are mounted on.
A 295 tire is theoretically 295mm wide but they aren't really that accurate.

I don't know if it's cool to plug another forum so I won't link it but there's a forum for Cummins powered trucks (easy enough to find it) that has a dedicated wheel and tire section for specific body style Rams, I'm sure you can find out everything you need to know there just like you can find out everything about more RV-specific issues here.

and you're allowed to poke fun at Fords over there :)

Cabman,
I missed the memo on the year of your 3500 and whether it's DRW or SRW. This makes a difference on what size tire will fit.
I just put 315/75R16 AT3's on my truck. The tire, at least in this size is heavier than most MT and AT tires of the same size. Why? larger tread blocks and smaller voids. Air weighs less than rubber. The carcass seems heavier and by extension tougher than BFG AT's and others of the same size. I know you have 18's, which I wish I would have gone to, but to get the straight dope on the diameter, cross section, tread, depth, load capacity, be sure to go to the specification section of the tire mfgr. for that specific tire. Not one that's cheaper or close. Some other things to consider are availability around the country and the range of wheel widths for which they are recommended. You may have to do some digging but it's on the mfg.'s website somewhere. I originally ordered 295/75R16's for the same reasons you want them and the web site said only 8 tires in that size were available anywhere in the U.S. I said I would pay for the shipping from New Jersey to CA just to get them and they completely lost track of the tires in transit so I had to start all over picking a tire that had 50-or 60 available nationwide in that specific size. TBBW (tire buyer be-ware). Ask the dealer how many are available nationwide. What if you have a blowout in Ames Iowa? Are there replacements available?
Another thing to consider is the diameter change between old and new. I went from a 32" tire to a 35" tire with new heavier steel wheels in one pop. I went to this website to find out what rpm difference it would make in my gearing.
http://www.grimmjeeper.com/gears.html
They had the slickest version of a gear ratio calculator anywhere on the net. Just fill in the blanks. Pick your transmission, gear ratio, tire size and off you go. It was kind of like a video game when you change one number everything rattles around to the next readout.
What I found going from 32" to 35" tires (stock were 31.5") was that my gearing was now too tall to carry a camper successfully and use all 6 gears in the box. I have 3.54:1 pigs. By going to 4.10:1 diffs, it turns back the clock and makes the final drive the same as it was before. That'll never happen again. I was turning 1600 rpm @55 mph in 6th gear, with the 3.54's and 32's. With 4.10's and 35" tires it will be 1603 rpm @ 55. Lucky indeed.

So, there's more to it than meets the eye.
However, I probably have a different paradigm than you regarding tires. I want lots of sidewall for lowering the pressure and driving the 10K pound white brick on sand...and the dunes......and miles of beach,...@20-25 pounds pressure. I know, it's a weird and wacky desire, but I've done it for a while with super singles and find out that a mud tread is not as good on sand as a tread with a ratio of more tread block and less void. There is a reason the old-timers called big knobby tires: "Grave Diggers".
I'm thinking the AT3's will give more miles of use than a big void tire and still work O.K. on snow. BTDT. Jeanie has the AT3's on her 2011 Grand Chero Limited, and they have given way more miles that I expected. 50K+ miles. My son Matt also runs them on his 2001 Grand Chero with the resulting same high mileage.
jefe

Bingo! Actual tire dimensions - for a given size - vary widely from one brand/model to another. And they also vary depending on the wheel width they are mounted on.
A 295 tire is theoretically 295mm wide but they aren't really that accurate.

Good point.
A load carrying tire needs a wheel width that closely matches the tires tread width. This insures a flat running tread and more important is this insures the ideal position of the sidewall (verticle) for carrying a heavy load all day long at highway speeds.

I have no idea how wide the OP OEM wheels are but the 295/ AT3 Cooper shows a 9.43 tread width. A 9" wide wheel would be ideal for carrying heavy loads.

You won't notice a significant increase in stability other than the peace of mind of having good heavy duty tires. Size wise they will fit fine and are a good improvement over the OE tires.
Will throw speedo off a small amount. Couple mph at highway speeds.
Don't waste your $ on a matching spare unless you want to put it in the rotation. Not needed for a small change in diameter.

Jefe, did you actually gear down for the bigger tires? Or just speaking theoretically?
Also to improve your snow traction significantly, you can get them siped.
I believe siping is a good addition to most any tire short of a dedicated snow tire with the only downside being increased treadwear when hauling heavy (camper). That's the only tradeoff in my experience.

Good points jefe. I was not thinking about availability. I used to carry 2 spares but will probably only have one for this truck until the first time we are in the middle of nowhere and I have a flat. Actually, I am sure I will add a receiver hitch up front to haul another spare. The Firestone tires the truck came with are just an unknown for me and therefore I do not trust them and we get off the beaten path quite often, little less now that we have gone to a hardside TC vs. our popup we had for years. The Cooper St Maxx sure look good! I appreciate all the replies.

Cabman, agree those OE Firestones aren't very confidence inspiring. Fwiw, I've packed on a lot of miles on a set of Transforce ATs with a heavy camper on the truck. They've done good. All pavement pounding though.
When we went to AK, the truck wore a heavynset of Toyos though.