2nd Gen Non-Engine/Transmission 265/75 -->> 285/85 MPG difference ??

[Katmandu]

My truck has 3. 54 gears, 5 Speed and 265/75-16s. I'm pondering going to 285/85s to help the Highway Fuel mileage.

I know going to 285s will be 1. 5" increase tire height and around 150 RPM decreace in RPMs. Overall around a 10% difference from the 265/75s.

My question is whether or not it's worth the $$$ and trouble to go for this tire upgrade.

What (if any) MPG difference could one expect ??

 

[Katmandu]

Anyone ??

 

[JFaughn]

You might gain 1/2 that becouse of pushing bigger tires , especialy in mud and snow , now your plowing , taler skinnyer , leave out the wider , unless your compromizing one thing for a nother.
Its hard to have your cake and eat it too .

 

[bkroupa]

I went from 245's to 285's when I still had 4. 10's & the difference was ~. 2-. 5 mpg at best.

 

[RAMICATOR]

i had the michelin ltx 265's and went to the firestone destination mt's 285's and lost 1-2, but thats a mud terrain for ya.



what tires are you planning on getting?

 

[Katmandu]

i had the michelin ltx 265's and went to the firestone destination mt's 285's and lost 1-2, but thats a mud terrain for ya.

what tires are you planning on getting?

Did you correct for the Odometer when you swapped to the larger tires ??

Not sure yet on the tires.

 

[kscheffler]

I am also looking into moving up in diameter but if it is only 0. 2 to 0. 5 increase not worth it. Does anyone else have any data for mileage with increased tire diameter? Given the extra cost for the 85's it will take a lot of miles to just recover the cost of the tire then maybe you will experience a pay back on your tire investment?

 

[bkroupa]

One of the reasons I went to 285's was carrying capacity, look at what 285/75 D tire is rated at. It handles my 30' TT with my 800# motorcycle in the bed no problems & rides well. One thing I noticed that helps explain why the mileage didn't go up that much is the difference in rolling resistance between the 245 E's & these 285 D's.

The difference I've noticed is with the 245's I would roll on my driveway & at many traffic lights by gravity, once I stop rolling with the 285's it does'nt start rolling as easily like it did before. The larger tires are smoother riding & did reduce my engine RPM's by 10% which did reduce the engine noise in the cab some. Now that I've swapped to 3. 54 gears (which is the best mod I've made to the truck, I gained a solid 1 mpg at 65mph). I like the 285's running empty, but I think the 245's or 265's might give a better final drive ratio for towing at speeds below 65mph.

 

[FDNYMOPARGUY]

I recently went from 285/75 to 255/85 to 265/75. (yeah, everyone says I change tires like I change oil) The best milage was with the 285/75(19-20 mpg). 255/85 was too tall(17-18mpg), 265/75 was too short(17-18mpg). This is with 3. 55 gears. I'm going back to 285/75 soon.

 

[Katmandu]

I recently went from 285/75 to 255/85 to 265/75. (yeah, everyone says I change tires like I change oil) The best milage was with the 285/75(19-20 mpg). 255/85 was too tall(17-18mpg), 265/75 was too short(17-18mpg). This is with 3. 55 gears. I'm going back to 285/75 soon.

How did you correct the speedo/odometer when you went to the larger tires ??

 

[FDNYMOPARGUY]

The truck is calibrated for 265/75's. Using GPS I found the 285/75's slow the speedo/odo about 3. 5%. The 255/85's by 5%.

 

[klaybus]

Tires

I just went from 285s to 295s & lost 1. 5-2 mpg! Probably a bit less since running winter fuel but it sure wasn't a welcome drop in MPG. I think next time I'll stick with the 285s FWIW. Rolling resistance?

 

[Sixpack]

Rolling resistance?

And more weight to get rolling... .



Don't do it for the mileage increase... you most likely will be disappointed.

 

[terrywerm]

This may not be the best comparison, but I had been running 285/75R16 with a mud / terrain tread, and they were good tires, but I only got about 15 MPG during the winter, and that was after correcting for the odometer error. Now I am running 265/75/16E with a much less agressive highway tread that is also mud and snow rated. My mileage went up to 18 during the winter months. Added an EZ and I'm now up to 20. 5 - on winter fuel.



Since I also tow, the 285's would probably be too tall, especially with the 3. 55 gears.



The 285's might increase your mileage if you stick with a tread pattern that is not highly aggressive, but I'm planning to stick with the 265's.

 

[Kwoolley]

I went from 265 to 285 and liked the decrease in RPM. Then I got wickedly stuck in a field due to rain saturation. I have since went with 305/70's for the added floatation they offer. I love that Cummins, but it will act like an anchor given 1/2 a chance. We live right next to Pismo Beach and I noticed right off that the truck would stay on top better with the 305's. Keep in mind that mileage is zero when stuck.

 

[FDNYMOPARGUY]

305/70's would be nice, but I need my front end to last. From what I've been reading 285's are the best compromise between flotation and longevity of front end components. Also, 285's are available in E range - 3750 lbs. per tire.

 

[mcoleman]

I went from 265s in the Mich LTS load range E to an all terrain 285 D and lost about 1 mpg. But the truck gets around on the farm better.

 

[Katmandu]

305/70's would be nice, but I need my front end to last.

What would 305s be harder on front end parts ??

 

[MPerez]

Have 285's - should have 245's

My truck had 285 75 16's on it when I got it so I can't tell you if there is any improvement over stock. I run the tires at nearly the full inflation pressure (load range "D") and could get up to 22 miles per gallon (corrected for speedo error). I used a GPS and found that I had an 8% error. I just bought some 265 70 17's to install (wanted load range "E" and shorter sidewalls) and I will check the difference with a GPS with them.



My door sticker claims I should have 245 75 16 tires. My friends 99 3500 should only have 235 75 16's on it... Must need clearance between the duallys.