Dang you have better gas mileage with the new tires then I have with stock.

 

MPH and Odometer can be set to any new tire size at your dealer for about $20. How do you think they get it accurate for the dakotas that COME with 265/70-r16 from the factory? I have 265-75-r16, and there about an inch taller then your new size and I didnt loose any gas mileage. Your not doing any harm to your pickup truck with new tires, the computer can stay off as long as you like, then you can go get the MPH/Odometer calibrated at your leasure. Its not off that much trust me, this was no more then a 5% rolling change. Maybe at 60mph, your really going 64. and at 30 your really going like 32. No biggie. Like i said 20 bucks fixes all this.

245/70-r16 is a pathetic size for these trucks to be running, its way to small for the mass of the frame and body. Not only does it look silly, but its a simple sacrifce by dodge in the name of road comfort/noise.

I cant believe that you lost that much mpg just by this small tire diameter change. Think about it, dodge doesnt change the MPG sticker ont he windows whether you buy the St model with 245/70 or the SLT model with 265-70. Its not THAT much of a difference.

 

I lost a similar mpg when I went to 33x12.5 BFGs. Like stated earlier, the mpg calculated be the truck will not be accurate if you haven't reprogrammed the difference.

 

Yep a 2-3 mpg difference sounds right. Rotational mass is a killer especially on a truck that is already underpowered. I can't wait to step down from my 265/70's to a 245/70.

 

well I won't disagree...


sounds like it is to be expected, but I was surprised given it's a factory option sized tire... of course, sounds like the calculations are off as well so it's probably not as bad as i think... thanks

 

from the tire rolling resistance section of the MPG FAQ:

TIRE CHOICES for BETTER MPG

Increasing the air pressure in your tires, and picking a narrow 'rib tread'
commercial delivery truck type tire that has low rolling resistance
definitely will help MPG.

Raising the air pressure by 15 psi to the max 70 psi in Goodyear Wrangler
HT 235/85R16E tires increased my mpg by +1 in a 311 mile
test run - but the ride was bone jarring. A narrow, highway rib tire like the
HT gives the lowest rolling resistance. Wide, aggressive tread tires can be
three times harder to roll. It might pay to have a 4 tire set for the weekday
commute, and a weekend mudder wide tire set.

Several Cummins Diesel Ram owners have reported that buying special
wheels and converting to 19.5 Commercial truck tire designs have
improved both MPG and tire tread life - but these tires are generally
heavier. RicksonTruck is one such special wheel seller:

http://www.ricksontruck.com/

Consumers Reports is the only organization I know of that tests for rolling
resistance of tires but even they do not report the Crr number.
Quote from CR:
" Fuel mileage at a price. Some tires roll with less drag than others. The
lower a tire's rolling resistance, the more fuel you can save. Those savings
can be significant. {Pickup and SUV} Tires with the lowest rolling resistance
delivered nearly 2 mpg more at a steady 65 mph in our highway tests {2003
four-wheel-drive Ford Explorer XLT 4x4} than those with the highest rolling
resistance. The catch: While some high-scoring tires had low rolling
resistance, most tires with the lowest rolling resistance also had lower
overall scores."

In their 11/2004 Pickup & SUV tire test CR the
lowest rolling resistance tires rated 'excellent' were the:

Bridgestone Dueler H/T (D684)
Michelin Cross Terrain
Continental ContiTrac
BF Goodrich Radial Long Trail T/A

The Pickup & SUV tires with the worst rolling resistance were the:

Pirelli Scorpion STA
Kelly Safari Signature
Yokohama Geolander H/T-SG051

A tire with a 'very good' rolling resistance and high scores in other handling
and braking tests was the Hankook DynaPro AS RH03

Hankook recently announced that they had spent $10 million developing a
tire called the fx-Optimo that has even lower rolling resistance and can
give up to a 3% MPG improvement:

http://www.moderntiredealer.com/t_in...p;storyID=5961

In another test of "All Season" tires in November 2005,
CR rated these tires as 'excellent' for low rolling resistance:

Michelin X Radial DT
Michelin Agility Touring
Michelin Harmony
Hankook Mileage Plus GT H707
Kumho Touring 795 A/S
Toyo 800 Ultra
Sumitomo HTR T4

In the same November 2005 issue
'All Terrain' tires were also tested
but only the
Continental ContiTrac TR
got an excellent rating for low rolling resistance in this group.

The California Air Resources board is pressing the tire companies to make
rolling resistance measurements on tires freely available to the public by
2008, one of the few reasonable things CARB has ever done in my opinion

The lower profile 17 and 20 inch tire designs used on the 2003-2005
5.7Hemi Rams have a 'sticker' tire tread and higher rolling resistance than
earlier year Rams. It is probable that if a manufacturer makes available a
235 85 R17 tire in Load Range E it would be lower rolling resistance
than the stock tires and might improve MPG by 1-2 at 70 mph.

The 2006 Ram press release says the new model will have 'low rolling
resistance tires.'

In April 2006 the "independent and non-partisan" US National Academy
of Sciences completed a report on the rolling resistance of tires and how
MPG for the entire country might be easily improved if tire makers
increased their research into how to make tires roll even easier.
The 'meat' of this report starts about page 50 at this weblink:

http://www.trb.org/publications/sr/sr286.pdf

 

I say to Hell with rolling resistance lol. All this is gonna do in the appearance is make tall but less wide tires that have weak pavement tread on them! lol I want the beefiest most bad-@$$ looking tire they make, and I'm sure the rolling resistance is horrible beyond belief!

 

Great info HankL!

I was just going to add... it's the resistance, not the size that counts