Hello everyone, I am contemplating switching from 235/85/16 tires to 285/75/16 for more clearance/wider stance/better appearance on my 02 cummins. I am leery because of many things though. Will I see a increase in mpg because of greater circumference, or will it decrease because of more tire to move? Also I commonly cut and haul firewood so I sometimes am pulling a trailer that weighs 12-15k pounds. Will this cause a significant loss of power fully loaded with bigger tires? Currently I get 19.2 mpg empty cruising at 60mph @1750rpm and 15mpg loaded @ 70mph. Any input is greatly appreciated. Oh and will the rims I currently run be suitable for the 285's? I think the 285's recommend a rim 1" wider than what I currently run. Thanks.

 

When I got my 1995 it had stock 235s on it. I wanted to upgrade tire size but had the same concerns you do so I went with 265/75/16...but it didn't give it the look I wanted. The tires still looked too small. So a month later I went back and put some 285/75/16s on. Now it looks good, has a way better stance and I can't tell any difference from the stock tires. No loss of power, no oddball shifting or gear hunting and no change in fuel economy....drives like it always did. Your 2002 is way more powerful than my 1995 so I can't see that a 33 inch tall tire would have much effect on it. And for what it worth I owned a 2002 from 2006-2012 and I ran 33x12.50x16.5s on it the whole time I owned it. I often pulled 14000lbs with it, it had a plow, toolboxes and a heavy steel flatbed and was always good on fuel. Way better than the 2012 I replaced it with.

 

Thanks for the input, sorry for the delay. I ended up going with the 285's. They look good, have a good stance, and I don't see a huge power loss. I ended up going with Telstar Trail Cutters. I'll post pics on my profile later. Super happy with them so far. Went to try out and walked through 18+ inches of drifted snow and slimy mud like nothing. Hopefully they wear as good as they have traction

 

Have 285 x 75R-16E on my '02 RC ...... 4x4

Went with Michelin LTX M/S2 ....
They need at least an 8" rim.
Extremely smooth, with no loss of power, no rubbing, and no issues ....
My truck is basically as yours is ....... 5sp with 3.54 cogs.

 

I talked with my local tire shop that I've dealt with for forever and they said I didn't need the wider rim. I have noticed these rub just a bit (20/32's of tread) so I will be getting a leveling kit so I don't tear up mud flaps and the body with chains in the winter. Weighed the tires and came up with 96 pounds, but I have steelies. I'll find out tomorrow on mileage and power loss. Here's hoping.

 

285's are very comfortable and will react almost like stock. That said, most trucks came with either 245's or 265's already..... And the 285's are the widest you want on a stock rim. Guys try to mount sizes like 305's or larger and they narrow stock rim will cause the tread to bow and wear poorly.

 

Yep. I even get premature center wear with my 285's due to high psi I run due to the camper. An 8.5-9.0" stock rim sure would be nice.

 

Alrighty. Took the first good hauling test with them yesterday and hauled 6500 pounds of wood a hundred miles or so. Didn't notice but maybe a little power loss on steep grades (I live in the mountains). I haven't filled up but I think I will get 13-14mpg which is pretty close to what I got with stock size.

 

Get yourself something like an Edge EZ and you'll not only regain the HP you think you lost but you'll discover how wonderfully easy the Cummins can tug things around like its truly capable of.

And not to get your thread off-topic but I'd highly suggest that you throw away your K&N before it not only hurts your turbo and contaminates your intake system but its not doing anything to help airflow. K&N's and charged engines are not a good combination.

 

I have 285's on my 01. Even with factory alloy wheels they look too wide. I prefer narrower tires anyway. After a lot of digging, I finally found a Canadian web site that listed the vehicle manufacturers recommended tire pressures for most vehicles. For the stock 265 on my 01, the pressure is 54 on the front. With the 285's, I'll try running 45 in the front and 55 in the rear and monitor the tread wear. These are the same pressures I run on my 92 with 235's.

 

I've always felt that running tire pressures will be determined by the specific tire and the specific vehicle they're on. Not all combinations are the same. All the charts out there are good guidelines too but in reality I've found them to be widely inaccurate for specifics.

I base my tire pressures on how the tires sit under the vehicle and how they wear. Most certainly its nice to have them set really soft so the ride is smooth and cushioned but thats not always the right choice for the tires. So wear patterns is what I use. Surprisingly my E rated 285 TOYO M/T's wear very nicely and I only rotate them front to back every 5000 miles or so.

That said, I usually run 65-70 psi in the front tires to support the heavy truck cab and 1100 pound Cummins, and 50-55 psi in the rear because unloaded trucks dont need that much support. But.....when I hook up to my 5th wheel, I pump the rears up to 80-85 psi so they run cooler and offer the best support possible for my heavy trailer.

In point.....what works for me may not work for all of you.

 

It depend on the tire construction a lot. As I had no starting point (MIA door sticker and nothing in the owners manual) I went by what the tire shops were telling me. Now I have a set of ruined winter tires due to being way over inflated for the truck. I drive approx 500 mile a week. I should be able to see on the measuring stick now, how they are wearing week by week. Ya, trial and error. But you have to start somewhere.

 

My Toyo MT's were stronger than these AT2's. Sidewalls were thicker and after 700 miles stuck like glue with zero squirm. I just like a quieter tire. The shop I use is getting really good feedback for the RT's. Noise level is a dab above the AT2's which is surprising to me based on the voids. The Nitto Exo Grapplers are catching my eye too.

 

I saw those R/T's and they do look nice.

 

Katoom,
I also saw some 37" RT's which for whatever reason Nitto made into a D rating. Much thinner sidewalls.
The 35's on a stock rim just appear to be pinched in at the bead.
The shop is a Cooper distributor also. I'm hoping a Cooper ST Maxx tire comes in.