i just traded my 20's for factory 17's and looking to get new tires, currently they have 245/70/17 . my main purpose of the trade is for better towing, all the searching i have done the main question i find is whats the biggest tire to you can run on a 17 which isnt helping me any. im looking to see if anyone can tell me how much of a difference im going to see towing between running a 265 series tire over a 245 series, i would like to use a 265 series unless its going to cut me down a good amount on towing , trying to do my homework before spending my money on a tire size i wont be happy with. any insight is appreciated

 

265/70-17 was an oem size available from dodge along with 245/70-17. The 265's will be about an inch taller but you're still a lot better off than 20s. I would personally go with 265's, that's what I have, gives you a little more width to work with for distributing weight.

 

Overall diameter is what you should be focused on. 245 and 265 is the width of the tire, not the height.
Look Here for more info.

 

The 265/70R17 will reduce your effective gearing by 3.5% over a 245/70R17. If you have the 3.55 gears, that can start to get pretty low. If you have 3.92's, you'd be looking at the equivalent of about 3.78 so still pretty good.

Don't be fooled by the 20's. If you have the 275/45R20's, they're actually smaller in overall diameter which would help keep your rpms up for better towing (about 2.5% higher). The drawback is that there's little rubber left between the rim and the road which isn't great for hauling. All in all I'd stick with 17's. Go smaller for more rpms or bigger if you you feel you have enough power.

 

i have 392 gears, since the 17's are still new to me i wasnt sure what the best tire size to run is . far as towing i have a new 5th wheel that i havnt got to tow yet as well lol , 26ft 7000lbs so trying to make the right choice the first time with tires, what size wheels and tire are you running, i see you tow a trailer as well

 

I have the stock 245/70R17 size but in LT Load E's. When I bought the last set of tires, I had the 3.55 gears which wouldn't have handled the bigger tires all that well hauling my trailer. I prefer the smaller tire anyway for mileage and looks on my 2wd truck. I think most guys with the 4x4's run the 265 tho.

 

My 2005 2500, came factory with 265's and I jumper up to 285's on stock 17x8 aluminum. That is as big as I can go stock, without going to a wider wheel.

 

I've used the 265/70/17's on my truck ever since the factory 245's wore out.
Throw the Firestone Destination AT's or Goodyear Wrangler ATS on there and they look and handle great.
I only have a 2 wheel drive but I like the look of the 265's.

 

The factory 20's are approximately 33 inches high vs 31.5 for the 265/70s. That means you are picking up about 6% better gearing. The 17s will also have a higher load rating and the 265s will put a little extra rubber on the road over the 245s that you will need every bit of. I know what the picture book says about the trailer rating, but 7000 pounds is still a lot for a 1500. Remember the extra weight you will have in the truck with a tank of fuel, people and gear. Load rated tires are a must and good shocks have to be considered. If you haven't all ready, swap out any dino fluids.

Have a great time.

 

A 7000lb trailer with it's own brakes doesn't effect tire ratings at all as far as the truck is concerned. The only additional weight on the truck is the tongue weight. That's all. If you were to load up 1200lbs in the bed regularly, then yes, tire load rating is subject to be scrutinized. The push/pull while taking off and going around turns doesn't do as much as you would think. Even the cheap Class "C" car tires that come stock can handle the tow ratings of the truck if you can believe that..haha Cuz those are super soft.

Overall tire diameter effects towing more than the size of the wheels itself. While the wheel can play a very small role, it's the tire diameter that has the biggest effect on towing.
Factory 17's are rated for 1,000lbs more because they are only 31.5" in diameter
Factory 20's are 1,00lbs less because they are 33". Put 33" tires on 17" rims and your towing drops 1,000lbs just the same.

So, having 17's with 3:55 gearing will tow THE SAME amount as a truck with 20's and 3:92 gearing.
Having 17's with 35" rubber and 3:92 gears will tow the same amount as stock 20's w/33" rubber and 3:92's.

Lots of guys throw on 33/35"" rubber on 17's with measley 3:55gears and have reported towing is sluggish, but truck still pulls just fine while moving. I'd reccomend a HD trans cooler at that point.


Hopefully that makes sense and you can all follow?