I have a 2002 dodge 2500 4X4 with 4:10 gears. I am currently running 315/75/16 BF AT tires on 10" wheels. I am getting about 16.5 mpg. I also have a set of 3:55 gears. I am looking for some feed back on the best tire and wheel combonations for both sets of gears to obtain better MPG.

 

A tall skinny ribbed tire on an aluminum light weight rim with lots of air, and of course the lowest rpm possible without lugging.

 

What Rick said, except in town. Very tall tires will make it work harder off the line, during acceleration, but on the highway, will be best.

Chris

 

235/85-16.
These are about 33 inchestall, maybe a little under and depending on brand can be very skinny. Maybe too skinny some brands but you'll know if you see them on a rim.
E rated.
When I went from this size to a wider tire I lost 1.5 mpg. The cummins will not notice anything turning a slightly taller tire like this. Its the taller, WIDER tires that will really hurt you around town.

Big Jimmy

 

I run a BFG A/T KO in that size, so far I'm please with the ride, wear and traction. The tall narrow does IMO a much better job cutting thru the white stuff which we just got 24" on Sunday. I have noticed slightly better mileage with these versus the 265 I was running before.

 

I have 8000 miles on a set of 285/75 yokohama a/t geolanders and they are by far the best wearing performing tires I have tried BF Goodrich very vast wearing, bridgestone a/t duelers not bad but wear out faster than geolanders

 

Actually, this is more like a 31" tire, about the same as a 265/75-- just narrower. Do the math or look it up and you'll see.

www.tirerack.com

 

I am getting a new set of BF AT tires out of Discount Tire due to excess vibration. They told me the 315/75/16 tire is on back order. They want me to go with a 305/70R/16. What do you guys think??

 

What do you think? 1 size smaller.
Try to have your tires match mounted and road force balanced! If your tire shop don't know what this is find 1 that does.

 

What does that mean? I've never heard of it before.

 

You need to look at what the use of your truck is to determine the best tire for mileage. If you are running almost all highway, a tire like a 235/85/16 is great. However, if you only drive around town at speeds less than 50 mph, you want a tire that is smaller than that. The sizing of tires has a few effects. It changes your final drive ratio which is the reason why you shouldn't be running short tires on the highway(although they are better in town). Tire diameter also effects rotational inertia which isn't a big deal once you are moving but is a big deal when accelerating. The final thing that tire size plays into is windage. A lower truck has less windage so running tall tires will increase windage by raising the truck. Also, wide tires will significantly increase windage.

As far as tread pattern goes, you want something that is really smooth(not an off-road tread) and has a hard rubber compound. Tires with a smaller contact patch are going to give better mileage. To help with this, make sure you are running the tires at high pressure.

Rims can effect both rotational inertia and windage. A lightweight aluminum rim will have the least rotational inertia. Covering over the outside of it with something flush to the tire will great reduce windage.

 

keep your 315 tires. Unless you are going to put the 3.55's in. You might put some info in a sig, so we know what your running, tranny wise.
If you go with a smaller tire with those 4.10's you will rais your rpms. In my 2nd gen I am at 2500 rpms @ 70 mph., thats with a 245/75R-16 tire. Witch is a 30.5" tire. A 235 tire is equal to a 30" tire, not a 31", or a 33". Check it out.
So dont go with a smaller tire if you want to gain mpg on the hwy. You wont get it with 4.10 gears. For tire selection go with a good A/T tire. I run Toyo A/T's. I gained 3 mpg when I put them on my 1st gen. They replaced some BFG's. and keep your tire at max psi. it will help keep resistence down on the road.

 

i got 235-85-16 and whats in my sig and you see what im getting, i also added a lower air dam. But its winter time, you have a 4x4, 4.10 gears and most likely an auto. try not to beat your brain figureing out how to get more mpg, just get a tire that you can use both on the street and be able to use your 4x4.

 

315's are not a good tire for even highway mileage. 315's are for use off-road or for looks. They are much too wide and have too large of a footprint and too much windage. They also have way too much rotating mass. RPM over 1900 or so on the highway will hurt you some but you aren't going to gain anything by going with big fat tires to decrease your rpms a little and your in town mileage will suffer greatly.

The 235 tires that we are talking about are actually taller than a 245 because the aspect ratio is 85 not 75.

If you really want to go for mileage, you will need to swap in those 3.55 gears. As crabbelle points out, you need to be happy with more than just your mileage. In truth, the easiest way you can increase your mileage is through changing your driving habits.

 

There's always the 255/85/16 option. They are like a 33 but skinny, and a lil harder to find. My budy has a set on his truck, they look nice, not sure about his mileage.