Jump to content

Fuel mileage on 285s

tyhuck

By tyhuck
in Tires, Wheels & TPMS

Recommended Posts

KMGZ400 Senior Enthusiast

KMGZ400

Posted
Posted

Went and got a set of 285/70/17 Wild Country XTXs. I like em. They have a tread pattern similar in aggressiveness to a NItto Tera-Grappler, and after the guy took some trade for my old 35s, I got out of there for $808, which included a used spare. Saved me about $200 and the hassle of having to resell my used ones. i hope that once I get the bumpers and the lift off, i can get my mileage back up. These new tires are only a couple more lbs heavier than the BFG AT 265s that were on the truck when I bought it, but WAYYYYY lighter than the 35s were. We shall see.

 

do you have a pic of them? id like to see what they look like.

 

are you putting them on your stock rims or the steelies? If i remember correctly your old stock rims were the same as the ones on my truck, I think the stock rims are a lot lighter then the steelies

  • Replies 44
  • Created
  • Last Reply
tyhuck Senior Enthusiast

tyhuck

Posted
  • Author
Posted

do you have a pic of them? id like to see what they look like.

 

are you putting them on your stock rims or the steelies? If i remember correctly your old stock rims were the same as the ones on my truck, I think the stock rims are a lot lighter then the steelies

 

 

Put em on the steelies. Dont have the alloys any more. The problem with the buildup of my truck was that I really didnt plan on downsizing in the furture, so I sold all stock parts. Stupid me, its the 3rd time Ive dont this. Only difference this time is that Im gonna have to keep this truck when Im usually stripping it down to get ready to sell.

tyhuck Senior Enthusiast

tyhuck

Posted
  • Author
Posted

Im still working on a picture. I keep forgetting.

 

I have no idea what fuel mileage will be since my speedo is still programmed for the 35s, but these new tires sure do make the truck more enjoyable to drive. Its smoother and doesnt try to wander as much, plus accelerations and braking take much less effort. Im starting to like this downsizing thing more and more. I bet once I get the lift and the extra weight off it will handle like a Corvette (not really, I know) compared to how it did at its biggest point.

zach1990 Senior Enthusiast

zach1990

Posted
Posted

Im still working on a picture. I keep forgetting.

 

I have no idea what fuel mileage will be since my speedo is still programmed for the 35s, but these new tires sure do make the truck more enjoyable to drive. Its smoother and doesnt try to wander as much, plus accelerations and braking take much less effort. Im starting to like this downsizing thing more and more. I bet once I get the lift and the extra weight off it will handle like a Corvette (not really, I know) compared to how it did at its biggest point.

Please post pics of how far they stick out on those wheels. I'm thinking about swapping my 305 buckshots for some 285s I've got of the same tire and putting them on those wheels you have

 

Sent from my SGH-I927 using Tapatalk 2

Big Whiskey Senior Enthusiast

Big Whiskey

Posted
Posted

I'm a little late to the party....but my '06 Z71 with the 5.3, 4 speed, and 3:42's got around 13-14 mpg with 285/70/17, D-range BFG AT's. I hope you have better luck than I did.

tyhuck Senior Enthusiast

tyhuck

Posted
  • Author
Posted

I sure hope so. I was getting better than that on 35s.

 

Here's some pictures.

 

4740A501-CC18-453C-AF26-43485B6C13D2-2197-0000019D9F056F08_zpsf01764ad.jpg

 

41AD8E86-C455-40D0-8505-1637849E6806-2197-0000019DA38A5DD9_zps75bff50c.jpg

 

C2A979A1-6B1F-4DA9-B100-CDF3230BAD2B-2197-0000019DA1545036_zps0060a1f0.jpg

 

735DD218-103A-4EEE-A63A-CA78E20A67C0-2197-0000019DA5D9E7BD_zps180f4b6c.jpg

 

A44D9A6F-9CD2-4B23-8F09-F0B9EC81CCE9-2197-0000019DA850521D_zps56e7d973.jpg

 

I think my truck body is shifted over an inch to one side, but even with that teh tires still run fluch with the fender flares. If you dont have flares, they may sling rocks with wheels like mine, but they should be flush with the fender on a stock wheel.

tyhuck Senior Enthusiast

tyhuck

Posted
  • Author
Posted

I think it happened when I put the lift on since I lifted it one side at a time. Thats the only thing I can figure.

 

 

Shes definately going on a diet as soon as I get some stock replacements. Supposed to meet up with a guy to do the swap on the 27th.

tyhuck Senior Enthusiast

tyhuck

Posted
  • Author
Posted

Don't forget, the weight and of the tires will affect MPG's. I went from the stock Goodyears and over to Bridgestone Revo's, same size, and MPG's dropped by about 1.5MPG. Somebody please correct me if I'm wrong, but unsprung weight (tires) will kill MPG's if it is too much.

 

I crunched the numbers and the tires that were on the truck when I bought it were 47lbs each (BFG AT 265/70/17 C), the tires I took off yesterday were 68lbs each (BFG KM2 35/12.50/17 D), and the tires I have now are 52lbs (Multi-Mile Wild Country XTX 285/70/17 D). I figured I saved over 64lbs switching to the 285s, and Im still only about 20lbs over the 265s. Thats just unsprung weight. Its not even factoring the difference in weight in the spares (had that swapped from a used 35" for a used 285).

 

If only it were this easy to shave lbs off myself.

  • 2 weeks later...
scottmoyer Enthusiast

scottmoyer

Posted
Posted

I get about 14.5-15mpg with my '06 Z71 with 3.42 gears on BFG AT KO in 285 series. The majority of my driving is short runs of a few miles here and there. I get 16+ on the highway cruising 70-75 when travelling with 3 adults total and luggage. My factory 265 series street tires gave me a best of 18mpg on the highway and averaged 16 around town. I saw a 1.5 mpg drop with the extra weight of the new tires and the extra tread pattern and an extra .5mpg drop when I cranked my torsion bars. Not sure if yours is or not. I want 3.73 gears to improve my mileage even more now that I have the larger tires and extra weight.

kstruckcountry Senior Enthusiast

kstruckcountry

Posted
Posted

I get about 14.5-15mpg with my '06 Z71 with 3.42 gears on BFG AT KO in 285 series. The majority of my driving is short runs of a few miles here and there. I get 16+ on the highway cruising 70-75 when travelling with 3 adults total and luggage. My factory 265 series street tires gave me a best of 18mpg on the highway and averaged 16 around town. I saw a 1.5 mpg drop with the extra weight of the new tires and the extra tread pattern and an extra .5mpg drop when I cranked my torsion bars. Not sure if yours is or not. I want 3.73 gears to improve my mileage even more now that I have the larger tires and extra weight.

Are you running P or E tires?

scottmoyer Enthusiast

scottmoyer

Posted
Posted

I think they are the D rated tires at 56lbs each. The max inflation of my tires are 65lbs, not the 80lbs of the E rated tires. The weight difference of the two is only 3lbs lighter for the D range. The factory Bridgestone Duellers were 40lbs each. Also, the BFG tires are about 1.1" wider of a footprint, so the contact resistance is higher.

scottmoyer Enthusiast

scottmoyer

Posted
Posted

I cranked the front end at the same time I upgraded the tires, but I originally had the Michelin AT2 tires that have a smaller footprint and less aggressive tread. I saw 1.5mpg loss with those tires and the crank. I'm down about 2mpg now with the BFGs and the torsion bar crank.

Archived

This topic is now archived and is closed to further replies.

Go to topic listing

  • Latest Articles

  • Posts

    • Grumpy Bear
      Vehicle Payments

      By Grumpy Bear · Posted

      How did all that extra get added? AI bot! 
    • KARNUT
      Vehicle Payments

      By KARNUT · Posted

      This is interesting. My quote tagged here is different from my original quote. After I’m driving them longer. That isn’t me. I don’t talk that way. I definitely wouldn’t express myself that way. Interesting.
    • UrbanRage
      What have you done to your K2 today?

      By UrbanRage · Posted

      I have the same running boards on my truck and I do agree they are bulky. I also find myself stepping over them when getting in and out of the truck. Besides providing protection to the rocker panels, they aren't very useful.  I will be replacing them soon with the Amp Powersteps. 
    • Grumpy Bear
      OCI, not when but why?

      By Grumpy Bear · Posted

      10 Ford and Chevy engines proven to reach 300,000 miles   You may note a common 3K OCI on this list of gas motors. I skipped over the diesels. Dh'O. 
    • jake111
      Gasser Subforum Has Been Quiet - - So, Regenerative Braking and Using L10

      By jake111 · Posted

      Thanks newdude!  By the time manual selection is needed, I'm probably too much of a control-freak to depend on the transmission sensing braking to activate automatic downshifting.  I would be anticipating the situation and already be manually downshifting.   This truck replaced a 2004.5 LLY diesel with the Allison 5-speed.  Putting it in T/H made noticeable differences (when the torque converter locked, upshift points, downshift behavior).  On this 2024 gasser with the 10L1000 I haven't been able to detect much, if any, difference.  Ok, I can never tell now when the torque converter locks up.  But I also don't notice differences in shifting.  For downhills, I've probably already manually downshifted by then anyway.  Since it's also more awkward (than the 2004.5) to engage/disengage I don't even bother.  Or maybe it doesn't really matter with just a 3k lb. camper in the bed?   Thanks also for the list of reasons the charging system might select various voltages.  However, what I am seeing doesn't fall into any of those categories.  It very definitely, and very consistently, rises after coasting/braking.  Maybe not immediately, but not very long after coasting/braking.  Very consistently drops voltage when no longer coasting/braking.  It might also be interacting with the camper battery charging (I might disconnect the camper and see if it changes the charging behavior).  I also need to recheck turning on headlights for when I want to force it to charge the camper.   Another JR, in June I converted the camper to LiFePO4.  Since it's not a good idea to try to charge lithiums directly using truck, I installed a Victron Orion XS DC-DC charger (which BTW is AMAZING!!).  Being cheap, I only had to buy that one item (besides the battery, of course) to do the conversion.  The camper OEM 120v battery charger (only 19 years old and works perfectly) and the truck feed the input to the DC-DC charger (not at the same time).  But I didn't want the camper charger feeding back to the truck so I kept the old separator.  I considered replacing the separator with a 30amp diode but that means more work and might add another 1/2 volt drop.  One thing that surprised me was the voltage drop over the long 10awg wire run, so I can only charge smoothly at 8 amps (because the DC-DC charger is completely configurable).  Another reason I don't want an added voltage drop with the diode.  I might also be a little lazy but all this work is being done under the sink with a small cabinet opening.    

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...