Mileage with 315's

[6 2 Carl]

After 5000 miles I am still not very impressed with my mileage. The highest I have gotten so far is 16. 4 (hand calculated). This was at 70 mph with a strong tailwind, flat ground, and driving like a weenie. With normal highway conditions my highway mileage varies from about 14-15. 5 mpg. Around town I am getting about 12. 5 mpg, but I have been driving quite hard in an effort to get the engine broken in as quickly as possible. I have also done about 1000 miles of towing a load varying in weight from 2500-8000 lbs.



Everyone I talk to thinks that my large tires are causing the poor mileage. I don't think larger tires should affect highway mileage that much, but since I had my 315's installed at the dealership I really don't know.



My question is what kind of mileage is everyone else getting with 315's and how much if any did the mileage drop when 315's were installed?

 

[jimnance]

Roughly lost 2 MPG in town and 1 MPG on the highway with the 315's. I sold mine and returned to the stock Michelins since I don't do any off roading.



With stock tires on my '03 HO I get 17. 5 to 18. 0 combined city/highway, and 20. 0 MPG pure highway at 65-70 MPH. This is hand calculated miles.



Towing is another matter. With the tall, heavy fiver behind me I'm lucky to get 10 MPG. Usually its 9. 0 to 9. 5 MPG. My driving is mostly in the mountains so I think I'd pick up about 1 MPG if I were towing on the flats.

 

[EEngel]

315's

I see a loss in town of 1-1 1/2 mpg and a gain on the highway of a little over 1mpg. 90% of my driving is HW, so it works for me.

 

[FDrake]

Try driving with the TOW/HAUL mode if you are driving under about 45 MPH. I am seeing about 2 MPH gain using the TOW/HAUL mode for in city driving. Strange.

Frank

Las Vegas, NV.

 

[SamPap]

FDrake:



Is this with 315's?



Sam

 

[Spooled-up]

Seems like the guys that lose some mileage are running 3:73 gears. I wonder if their is as much difference if you had 4:10's.

 

[FDrake]

Not with 315s. That is with the stock 17" Michelins. I have been running with the TOW/HAUL now for a week when I am going less than 45 MPH and reset the overhead and the mileage is about 2 MPH higher with the TOW/HAUL on. Still lousy compared to my 02 HO Stick.

Frank

 

[Fred Swanson]

Going from duals to the singles w/315's, I gained about 3 MPG. It's been about 5 tanks now, so it's being consistent. Lost some weight, that has helped more than the tires.

 

[KHaeckler]

35's

I put my current tires on shortly after I purchased this truck so I can't comment what the "difference" was. Currently I'm getting 18 in town and 20 hwy. When the truck was new, I was getting around 15-18. Yes, my speedo & odo have been recalibrated. I bet my mpg's would be better with 315's ?



Karl

 

[DDurant]

My 315's cost me approx. 1. 5 mph also - but at 10k miles, I changed to red line synthetic deisel oil - got back approx. 2 mph! As I live in the desert, I expect cooling will be better also.



2004 quad cab 4x4

 

[6 2 Carl]

Well I now have 6000 miles on my truck; I have seen an improvement in mileage. I am now getting 17-18 mpg on the highway @ 70 mph. This is on the overhead display, which reads about . 5-1. 0 mpg lower than hand calculations. I have recently changed all of my drive train fluids (Redline in the trans, Amsoil in the transfer case, and Mobil 1 in the diffs). I suspect that my mileage increase is mostly due to the new fluids.



I would still like to see 20 mpg on the highway under ideal conditions, but I guess I shouldn't complain too much, since diesel is currently 30% less than gasoline. ($. 699/L for diesel and $. 949/L for gas)



Carl