mpg change w/265 to 285 tires

[Saccowboy]

ive got a 48re with 3. 73's and have the 315's now and my in town mileage sucks @SS!!!! so i'm thinking about taking the level kit off and dropping the back two inches and running bfg 285/70/r17's.

im looking for some input as to what u guys have seen with the miles per gallon changes in town and on the freeway? i used to get 16/20+ before it was borken in around 15,000miles and now im getting 12. 5/17 with about 42,000miles. all hand calculated. thanks for the help guys.

p. s. any pictures with the 285's would be appreciated too.



Will

 

[LAMiller]

one thing to think about is unless you've corrected you speedo for your big tires then your odometer isn't recording as many miles! So in theory your mileage calculates to lower numbers

 

[CRUSH'EM]

Will,

Bought a used 04. 5 w/17000 miles on it and stock 265 BFG's. First tank out of it with this setup, mostly farm and city driving, got 14. 5mpg. Put on Cooper Discoverer STT's (new style), and providing my trip odometer isn't off, nor my calculator, the best I've gotten is 16mpg (this is empty not towing). This is assuming that the odometer is actually correct with the new size tires????????? Unknown how far off it is. But the overhead puter usually is within . 5 to 1mpg of hand calculated numbers. No pics as of yet, but could dig out the camera and snap some for y'as. Truck currently has 19500 miles. Lemme know.

Jeff

 

[JonathanBurk]

I'm pretty similar to your setup only I'm a 2500 with the 610 CTD... QC 4x4 3. 73, 48RE Auto.



I've only had my truck 3 weeks and am riding on the stock 265's. I have a bunch of used 315's in my backyard which one is at least suitable for a spare, but l've decided to go to 285's instead. Most people said they saw 1-1. 5mpg drop going from 265 to 315's in the research I was doing.



If I keep it below 65 I'll get 18+mpg with the 265's. Around town I'm getting 15's & 16's, but keep in mind, I'm brand new.



The new Powerwagon's come with 285/70/17 BFG AT's stock and it looks perfect to me. Look for some ebay pics or something... I saw one at a local dealer and despite claims of 315 superiority, 285's are what "should" come on these trucks. No rubbing whatsoever, mileage should be decent, and heck... my friend's Titan came with 285's stock, but my 3/4 ton diesel don't?



You may also want to check your fuel filter if you haven't replaced it too just to be sure. 12. 5 seems low to me even with 315's in the city, but my only experience with 315's was on my Hemi, and even then I was getting 12mpg in a 1500 so you should be doing much better than that.

 

[Coolslice]

I've had in this order 265's - 285's (33s) - 35's- and back to 265s... (Yes, I am an idiot :-laf )



The 285's work but what I found out is that w/ the 3. 73's you will tend to "lug" your engine quite a bit if driving in the 45-55 mph range. I think I managed my best hwy mileage with the 33's, but my best in-town has been the 265's. . The 35's were terrible in both areas. I lost 3. 5 to 4. 5 mpg. .



IMO, the 3. 73's come with 265's for the the simply reason of keeping the engine in the correct rpm range. It has nothing to do with looks. . If you have 4. 10's then there is a little room to play. . If you do most of your driving at hwy speeds, then I'd go w/ the 285's.

 

[steved]

I went from 245 stockers stock steelies to 265 stockers (aluminum wheels), then up to 315s on stock aluminums... my mileage, figuring it straight (no speedo correction), stayed at 18. BUT, I think between the 4. 10s, 6spd, and 600CTD it wouldn't... I can still make the truck shift in it's power range... the truck isn't doing it. I was running BFG A/T ko's



I'm back to 265s (traveling cross country nowadays), and it hasn't seemed to have changed, again with an uncorrected speedo.



Tires have a lot to do with mileage... if you have tires with a high rolling resistance, then you are going to use more fuel. And that varies tire to tire, manufacturer to manufacturer.



I was running with 45psi front (out of 50 psi max) and 30 psi rear (out of 50 psi max). It rode good and wore the tires good.



steved

 

[JCleary]

ive got a 48re with 3. 73's and have the 315's now and my in town mileage sucks @SS!!!! so i'm thinking about taking the level kit off and dropping the back two inches and running bfg 285/70/r17's.

im looking for some input as to what u guys have seen with the miles per gallon changes in town and on the freeway? i used to get 16/20+ before it was borken in around 15,000miles and now im getting 12. 5/17 with about 42,000miles. all hand calculated. thanks for the help guys.

p. s. any pictures with the 285's would be appreciated too.



Will

Switch to 285's, but don't take the leveling kit off. I had my Kore Chase system installed, with Kore Welds and 35" Toyos. I lost about 1mpg in town, and 2 on the highway.



I just switched back to the 285's for the upcoming winter, and immediately saw an increase of about 2mpg on the highway. I just came back from the HDDR and got 17. 8mpg at 80-85mph the whole way (not running a box). Pretty good, if you ask me.



It did take a couple of days for me to get used to the look, but I think it's much better than having that front end squat.

 

[milehigh.o.]

I did not see a difference in milage when I went to 285's. It sucked then and still does. Goto my readers rides link and you can see my truck with the 285's. I say keep the leveling kit, its definately on my to do list.

 

[1Tufdsl]

Pic's of my 285's in the link in my sig. I lost less than 1 mpg in town and on the highway. I get around 15-16 in town depending on how bad the traffic is and around mid 18 to 19 mpg on the hwy with around 11-12 mpg pulling our trailer. I switched to the 285's at around 6k miles and have 23k on the odo now and they're wearing great.



Karl

 

[Saccowboy]

one thing to think about is unless you've corrected you speedo for your big tires then your odometer isn't recording as many miles! So in theory your mileage calculates to lower numbers

yep ive already covered that one it was reset long ago and is within one mph, so i figure that is close enough for my calculations. thanks for the thought!





also i change the fuel filter every 10-12 thousand miles and clean the afe every 5-10 thousand. i did notice about 1 mpg increase with the tst on 1X1 but had to take it off to get it serviced. it just died on me and i couldnt get the truck started with it hooked up. so now just running the ez on level 3 till i get it back.

 

[Saccowboy]

Will,

Bought a used 04. 5 w/17000 miles on it and stock 265 BFG's. First tank out of it with this setup, mostly farm and city driving, got 14. 5mpg. Put on Cooper Discoverer STT's (new style), and providing my trip odometer isn't off, nor my calculator, the best I've gotten is 16mpg (this is empty not towing). This is assuming that the odometer is actually correct with the new size tires????????? Unknown how far off it is. But the overhead puter usually is within . 5 to 1mpg of hand calculated numbers. No pics as of yet, but could dig out the camera and snap some for y'as. Truck currently has 19500 miles. Lemme know.

Jeff

your odometer is probably a little off maybe a mile or two per hour im guessing. because the stock trucks are set to the 265 tires unless they have smaller ones on them. thanks and hope to see those pics soon!!

 

[TCrawley]

I lost 1. 5mpg.

 

[GHedrick]

Someone posted this site on another thread. http://www.miata.net/garage/tirecalc.html

I used my gps to check the speedo with the bigger tires and it was 2. 1 mph off, just like the site said. I went back to stock tires and wheels (my truck came with after market wheels) and according to the gps it reads correct now.

 

[Saccowboy]

GHEDRICK,

so u went back to the stock 265's or the 285's if it was the latter of the two what did u have on it before? your truck looks really good by the way

 

[GHedrick]

The truck came with the Akuza wheels and 285 tires. I will be using the truck off road hunting and camping and I didn't want the mud and rocks on the sides of the truck. I managed to get a set of take off stock wheels and 265 tires from an 06 cheap. They fit under the fenders better. I like the custom look but they are not practical for me.