Gas mileage increase going from Cooper AT3 to BFG KO2?

[94toy22re]

So all summer I have averaged 17mpg on my work commute running the cooper AT3. So 3 weeks ago I switched to the KO2 and my last two tanks averaged out to 19mpg running the same commute, it also feels like when you let off the gas it coast a lot further. Tires are the same size 265/70/17 and same load range. I was expecting a mpg drop due to the KO2 being heavier and more aggressive.

 

[riNR]

I run the KO2 tires on my work van and love them. They are so much quieter than my old BFG AT too.

 

[kojackJKU]

weight has alot to do with. I find coopers notoriously heavy, compared to the BFGs.

 

[Bear in NM]

I switched my Avalanche to KO2's from the tires that it came with, which were more like car tires in terms of tread, last year. I did not have enough clock time on the originals for "scientific" results, but the KO2's have at least not hurt my mileage. On my last trip to Colorado with a full out camping load and a 175 pound motorcycle in the rear hitch, I managed a tad over 17 mpg. This included 2 Colorado mountain passes, and I have 4.10 running gears. I never did any camping runs on the original tires, but around town here, and a trip or two on 55-65 mph highways and I never saw more than 16 mpg, unloaded.

Craig

 

[SilicaRich]

weight has alot to do with. I find coopers notoriously heavy, compared to the BFGs.

Kojack nailed it. That being said, BFG also is normally known to just be a lighter tire across the board compared to its competitors. It might be something with the weight being more evenly distributed and potentially the AT3s affecting milage due to wear.

 

[rayra]

The answer probably lays with 'rolling resistance'. Whether it's brand / model of tire or just that it's a new tire vs old / hardened, who's to say.

the weight difference in the tires should NOT be making a 10% difference in mpg, IMAO. The change in overall vehicle weight is negligible.

 

[RubiconGeoff]

Even though the tires have the same size listed on their sidewalls, you will find some significant difference in their real-world height. Inflation pressure also plays a significant role, not only in rolling radius but also in rolling resistance. The two different casings used by BFG and Cooper likely need different inflation pressures to make an apples-to-apples comparison between the two.

 

[alaska]

Even though the tires have the same size listed on their sidewalls, you will find some significant difference in their real-world height. Inflation pressure also plays a significant role, not only in rolling radius but also in rolling resistance. The two different casings used by BFG and Cooper likely need different inflation pressures to make an apples-to-apples comparison between the two.

You are completely right. The only way to know the true size of a tire, is to measure it yourself while mounted on the truck and under load, and it almost never corresponds to what is printed on the tire, sometimes it's a little less, other times A LOT less. And, as you say, tire inflation plays a big role, and rolling resistance intrinsic to the tire.

 

[Mundo4x4Casa]

The AT3's are indeed heavier. But why? Bigger tread blocks and smaller voids. Pretty simple. Also, the carcass seems heavier, thicker and tougher. Here are my new 315/75R16's, 34.49" diameter, 3860 load capacity: front 7.5" wide, bead to bead stock wheels, and rear 10" wide, bead to bead, Stockton steelies with 1/2" plate hubs called Power Wagon Wheels.


I've had several sets of AT3's on Jeeps and now on my XTC. They have a long tread life, in my experience and wear evenly.
When I recently dumped my aluminum wheels for all steelies, and changed tires simultaneously, the weight penalty is more apparent than ever. Why would I dump the aluminums?

With these super singles on the rear they are a bit too wide for normal jeep trails so subsequently the rims take a real beating.

 

[alaska]

The AT3's are indeed heavier. But why? Bigger tread blocks and smaller voids. Pretty simple. Also, the carcass seems heavier, thicker and tougher. Here are my new 315/75R16's, 34.49" diameter, 3860 load capacity: front 7.5" wide, bead to bead stock wheels, and rear 10" wide, bead to bead, Stockton steelies with 1/2" plate hubs called Power Wagon Wheels.


I've had several sets of AT3's on Jeeps and now on my XTC. They have a long tread life, in my experience and wear evenly.
When I recently dumped my aluminum wheels for all steelies, and changed tires simultaneously, the weight penalty is more apparent than ever. Why would I dump the aluminums?

With these super singles on the rear they are a bit too wide for normal jeep trails so subsequently the rims take a real beating.

Hi, it seems the picture links you have posted do not work, at least they don't on my computer. I'd love to see these pictures..as a matter of fact I have a thread in this subforum where I asked to see pictures of 2nd gen Dodges with 315/75R16's with no luck. Specifically, what 7.5" steel wheels are you running with the 315's and what backspacing? Aren't the stock steel wheels on 2nd gens 6.5" wide? I plan to run the same tires on a '96 Dodge Cummins...
So, what kind of mileage are you getting with the 315's and your setup?

EDIT: oops, the pictures work just fine now....

 

[doug720]

I posted this in the wrong thread.

While not exactly the same, I just replaced the BFG 33X10.50-15 KM2's on my 60 with KO2's in the same size. WOW! What an improvement.

I ran the old style KO's for years, and liked them. 2 years ago, I needed tires and there were no KO's in that size available, and they would not be available for several months, so I tried the KM2's.

The KM's look great, and when new, were pretty quiet, but very squirmy and somewhat wallowey - are these words? As they aged, they grew louder.

I decided to try the new KO2's, and found 4 of them mounted, balanced with tax, etc for $815 at Americas tire with a $100 BFG rebate, and another $50 from Americas Tire. So $165.25 each out the door!

I took my 60 on a late season Sierra fly fishing trip last week with the new tires. It was shocking how much better they rode, handled, drove, sounded, and best of all, I picked up about 1.5 mpg over the KM2's. All good things.

The squirm and wallowing were 100% gone, steering was easy and straight, and it was so quiet inside, very nice. I ran the exact same pressure as KM2;s and the older style KO's, so this was a fair comparison. It has been too long since I ran the old KO's to be fair in comparing them to the new KO2's, but I really like these KO2's.

I did nothing too serious off road, but miles of dirt roads, sand, some water crossings and lots of rocks and gravel, and they worked well, and again, the ride was really good, especially on wash board sections. Much better than the KM2's in my opinion.

Time will tell, but very satisfied so far.

 

[Mundo4x4Casa]

Alaska/California,
From 2000 to 2002 the stock 16" steel wheels on a 2 series Dodge Ram were actually 7.5" across; inside bead to bead. Why the change? First of all they had to change the cross section to accommodate the then new disc brakes. They decided to make the back spacing 6.25" to ease the pressure on the awful unit bearings. This made more of the wheel itself inside of the 00.0 offset, a good thing. I had a good look at my spare, which was that wheel made in Brazil. I searched around for a couple more that I could use on the front axle. $50 apiece. On the rear I had Stockton Wheel make up some 16" x 10" wide, inside bead to bead, 4.5" B.S., steel wheels with 1/2 inch plate center hubs with 8 on 6.5" with lug centric holes. These are heavy but have that 'stupid' high load rating which will come in handy once I get the camper back on.
In 2003 Chrysler Corp. went to a 17" wheel on all the 2 and 3 series trucks to make more space for the then larger 4-wheel disc brakes. It's a long sad story about my 10" wide front Stockton Wheels about brake clearance. It's a story of misunderstood intentions.
Here are the two wheel sizes, face up, sans tires showing the offset: note the more open cross section on the inside of the 7.5" wheel vs. the neck down on the 10" wide wheel early on. The brake clearance is what blew up my application. The tire in the background came on the truck as a spare.

jefe

 

[alaska]

Alaska/California,
From 2000 to 2002 the stock 16" steel wheels on a 2 series Dodge Ram were actually 7.5" across; inside bead to bead. Why the change? First of all they had to change the cross section to accommodate the then new disc brakes. They decided to make the back spacing 6.25" to ease the pressure on the awful unit bearings. This made more of the wheel itself inside of the 00.0 offset, a good thing. I had a good look at my spare, which was that wheel made in Brazil. I searched around for a couple more that I could use on the front axle. $50 apiece. On the rear I had Stockton Wheel make up some 16" x 10" wide, inside bead to bead, 4.5" B.S., steel wheels with 1/2 inch plate center hubs with 8 on 6.5" with lug centric holes. These are heavy but have that 'stupid' high load rating which will come in handy once I get the camper back on.
In 2003 Chrysler Corp. went to a 17" wheel on all the 2 and 3 series trucks to make more space for the then larger 4-wheel disc brakes. It's a long sad story about my 10" wide front Stockton Wheels about brake clearance. It's a story of misunderstood intentions.
Here are the two wheel sizes, face up, sans tires showing the offset: note the more open cross section on the inside of the 7.5" wheel vs. the neck down on the 10" wide wheel early on. The brake clearance is what blew up my application. The tire in the background came on the truck as a spare.

jefe

Thanks for the clarification about stock wheels' width and all the information you provided..I learn always something new from your posts.
Love your choice of color for your wheels...very distinctive!

 

[kojackJKU]

I think that after some serious consideration of all variables….I am going to try the 225/65/17 KO2 on my patriot. With those on stock wheels, spacers and 2" lift, it should get along in the B/C and still drive fantastic on the road. That is the first round of off road readiness going on the Pat.

 

[rayra]

If the new tires have a smaller circumference it could just be the difference in the odometer readings, too. Truck thinks it's going farther due to more rotations for the same distance.

/don't shoot me, I'm just the piano player