265/70/17? 285/70/17? 285/75/17? Thoughts?

[Bouma]

I am going to need tires again. I am thinking about trying to lower my RPM on the highway. My buddy has a 6. 7 with 3. 42 gears and he runs about 300 or so RPM's less than mine on the highway. I have a 5. 9 with 3. 73 and a 48RE. Will I notice a difference in fuel mileage doing this, or should I just leave it alone? I know most 285/70. 17 have a D rating and I don't really care for that either. If I install the larger tires will my pulling capability be affected at highway speeds? Just thinking out loud about tire's.

 

[SDrake]

Same question but for 4.10

I wish i could get to where you are now. I have 4. 10 and even there I have serious doubts that 285 will increase my milage because the increased rolling resistance and air friction will eat up the advantage of the rpm reduction. Stock tires will carry the loads (big enough already for the load) and handle better than the bigger tires IMO. We need a bigger diameter tire with the same contact area as stock tires. I have no actual experience, just listening and trying to interpret what I have been hearing.



Unless I hear from someone with actual experience, I will be researching larger diameter wheels and tire combos to see if there is one that is efficient. don't much care for bigger fatter look if it is not going to make it drive better on the highway. Now if I was off roading that would be a whole nother matter Wish I had the time and money to have some of that kind of fun. Some of those mudders would be awsome.

 

[jhenderson]

I have tried 285-70, and 285-75, and both cost me 1-2 mpg. In my opinion, rpm's are not the major reason for lower fuel economy, it's wind and rolling resistance. I plow snow on less than 2 gallons per hour. At that rate I should get over 30 mpg, but I only average 17. 5. Plowing averages over 2000 rpm and 1 foot of snow is plenty of resistance.

 

[Jim W]

I believe tread design will also effect fuel mileage. I just purchased a set of new tries for my truck and I researched tire size along with tread design for my replacements. I know that this tire is not the most aggressive tire out on the market and some members will say they do not look right for a pick-up truck. But I decided on load carrying ability, wear life and fuel efficiency for me. I choose the Michelin LTX M/S2 tires, LT265/70R17/E. These have a 70,000 wear life warranty and are rated 9 out of 10 for fuel efficiency against their other tires.

Jim W.

 

[TFucili]

My '05 has the 48RE with 3. 73 combo same as yours. I went to Toyo MT 285/75-17 and it has cost me 1+ MPG, and they seem to be wearing pretty fast to boot. Also, I did re-calibrate the speedo to match the tires, so my calculations are pretty accurate. I didn't put the tires on for MPG, and my truck has never gotten anywhere near the MPG that others here claim, so take it for what it's worth.

 

[MChrist]

Personally, I think the 265/70/17 size just looks too small for the truck. I went to 285/70/17 Nitto Dura Grapplers from 315/70/17 BFG KOs and gained maybe 1 or 2 mpg, due mostly to rolling resistance. I don't know how these Nittos in this size compare to stock size, though. I have no problems towing heavy, but I like to be around 60-65, since 55 puts me around (roughly) 1400 rpm.
Regarding rpm vs mpg, I don't personally think it's that big of a deal. I believe LOAD is the determining factor. If you switched to 2. 73 gears, installed a Gear Vendor overdrive and could go 65 mph at 800 rpms, you wouldn't necessarily get great mileage, since the motor has to lug/dump fuel/try to boost.
There was a magazine article a few years back (for what it's worth), that changed out a trucks gears to a 4. 56, because he had huge, tall tires. Supposedly, he gained around 3 mpg because his truck was now running in the butter zone, instead of lugging at an inefficient speed.
The way to look at it is like this: your vehicle requires X amount of power to drive at a given speed. Let's say 60 hp at 60 mph. Now, where is your engine the most efficient? Depending on year, probably 1800-2000. So why would you want to gear a vehicle to turn at a lower (or higher) rpm than that?
Gas motors are much more sensitive to rpm than diesels. If you are revving a gasser at 2500 rpms going down the freeway, you are probably also pulling 20 inches of vacuum at the manifold. 20 inches of vacuum takes a lot of power to produce, so you are sucking fuel to keep those rpms high. The same vehicle with highway gears will just lope along comfortably at half those rpms and half the vacuum, thus sucking less fuel.

 

[MuddFlapp]

Big Tires

I have these on my truck and the Mileage is around 15-16. Also the steering drifts or wanders if you will. Did yours do that with the big tires? Or is it something else I have going on?



Thanks,

 

[MChrist]

Mine drove absolutely perfectly with those 315s on. You must have some loose parts on your front end.

 

[AWeiman]

we got about a 1mpg less running 285's on our 06. i will be the first to admit the truck looks much better with the larger tires, but the truck spends 80 miles a day on the road so the mileage was a little more important than looks.

 

[seafish]

we got about a 1mpg less running 285's on our 06. i will be the first to admit the truck looks much better with the larger tires, but the truck spends 80 miles a day on the road so the mileage was a little more important than looks.

This has been my my experoience also, but I am still running the 285. 75/17 E rated Toyo. If diesel prices keep going up, this will be my last set and I'll go bakck to Michelins AT2 or M/S in the oem size, even though they LOOK ridiculous !! :-laf

 

[Quilbilly brian]

I run 265/70/17 on my rig. They do look small but I get better mpg. I was running 295's and hey it looked cool but was costing me in gas. Seems the truck likes the 265's better

 

[Regcabguy]

Going from a 285-70-17 to a 285-75-17 cost me 1. 5 mpg. Switching to a MT killed another 0. 5 mpg. They look great,but are killing me at the pump.



Can you say 275-80-17?



Anybody notice that the last go around w/$4. 50 diesel a barrel of oil was $150? It's what,$112 lately? NICE!

 

[Bouma]

Thanks for all the info Oo. After reading this I think I will stay with the 265/70/17. With fuel prices the way they are I am looking to gain mileage not lose it. Even though oversized M/T's look great, I can't afford to loose MPG. I am thinking of Firestone Transforce AT's, Thoughts?

 

[DennyDay]

Thanks for all the info Oo. After reading this I think I will stay with the 265/70/17. With fuel prices the way they are I am looking to gain mileage not lose it. Even though oversized M/T's look great, I can't afford to loose MPG. I am thinking of Firestone Transforce AT's, Thoughts?

Try to get a price on Nitto Dura Grapplers, try Discount Tire On Line if thy are not where you are. Had 285x75R 17 and the RPM's at 65 were 1500RPM swapped with my son and put 285X70R 17 and RPM went up to 1850 @ 65 mileage alot better - - empty (no trailer)I can get 20. 5 and have gotten up to 22. 5 really worked at I to get it up there - - Ran from Victoria,TX to Mobile,AL and back

 

[MuddFlapp]

Mine drove absolutely perfectly with those 315s on. You must have some loose parts on your front end.

That's what I think also, well, back on my head.



Thanks

 

[rbattelle]

Has anyone tried the Michelin LTX series in 285/70/17? Same tread as stock, but a little wider and taller.

I'd like to move to those (when it comes time), but would prefer to avoid a fuel economy penalty.

-Ryan

 

[Regcabguy]

Another D rated tire. Michelin doesn't seem interested in offering an E rated truck tire in a 285 configuration.

 

[seafish]

Another D rated tire. Michelin doesn't seem interested in offering an E rated truck tire in a 285 configuration.

#@$%!#@$%! x2... that's the problem with Michelin oversized tires for our trucks !!!

 

[rbattelle]

Another D rated tire. Michelin doesn't seem interested in offering an E rated truck tire in a 285 configuration.

True, but it has the same load capacity as the 265/70/17 E-rated tire. 3195 lb, I think.



-Ryan

 

[Bouma]

So many people in love with Michelin. I always have had good life out of them but they always are very hard and don't grip to anything other than dry pavement. I know one of the local truck lines stopped using Michelin for this reason. They had many drivers complain about how they don't grip the wet roads. They had one driver pile up his rig, now they will not use Michelin. I see lots of Toyo's, Firestone's and Goodyear's around these parts. I love the grip of my Goodyear, hate the tread wear and the ability to balance them and keep them balanced. I think I will try Firestone's in a 265, I'll report back after some mile how they are working out.