Gas mileage increase going from Cooper AT3 to BFG KO2?

[jeep-N-montero]

The ko2's have been verified as having a smaller diameter/circumference and lower tread depth than the original ko's and other tire brands in general, so this will result in more revolutions per mile and a higher odometer reading as a result. BFG has always been notorious for producing tires that are not true to size, so I am not at all surprised if the ko2's followed suit.

 

[doug720]

On my mileage, I use my GPS to figure the mileage correction percentage. This is done on a flat 10 mile road section. Between the KM2's and KO2's, the correction was 12.9% for the KM2's and 13.2% on the KO2's. That's pretty close.

In addition, I have made cruising speed marks on my speedo and tach. My cruising MPH reading RPM's are basically the same between the tires.

I have tracked every tank of fuel I have ran in my 60 since the I did the diesel swap over 50k miles and 6 years ago. I have averaged just over 19.4 mpg. On this trip of 677 miles, one I have made many times, I averaged 20.8. Dam good IMHO for a loaded 60 with a roof rack.

I had noticed a MPG reduction when I switched to the KM2's from the old style KO's. I think a "All Terrain" tread tire roles easier than a mud type tire. When driving, or even moving slowly in my driveway, the KO2's seem to roll much easier.

Even discounting all that, the noise and ride are SO much better than the KM2's, it worth it to me!

 

[kojackJKU]

Oh for sure. If you do not NEED an MT tire, then there is no reason to put them on. A/T is fine for 90% of off road travel.

 

[Regcabguy]

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

I'll be interested how the AT3's work out for you. You really give them hell from your photos.
After having a near catastrophic accident with Bridgestone AT's on my 2nd gen. Cuts, flats leading up to a complete tread separation.
I've ran Toyos for ten yrs now without incident but I doubt if my tires approach 10% of abuse yours do.

 

[rruff]

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

As rayra mentioned, weight of the tire has almost zero to do with it. Rather it is rolling resistance due to hysteresis (internal friction). Stiff and tough casings along with gnarly tread contribute to higher resistance.

I'm surprised that the KO2s would be that good. They must be using good construction and compounds. If you figure 17 vs 19 mpg, 10k miles/yr, and $2/gal gas, that's $124/yr in fuel savings, or $620 over a 50k mile life. It would definitely be worth paying a little more for the tires!

I'm really surprised that the rolling resistance of tires is not universally tested and the data made publicly available. It matters a lot!