Last week I went from stock 245 tires to 265 Toyo's. A couple observations after about 325 miles on the new tires. Ride seems to be about the same, truck looks better, new tires are more square at the sidewall so the truck does not seem to corner as good as it did. I need a slight alignment adjustment but side to side tire sway seems to have increased. Much better traction. Slight tire noise going down the Hwy.

I'm pretty anal about tracking my MPG's and do it every tank and keep a running average. But please don't tell "JJ" (JJsDuMax) because I've been making fun of his DP MPG rules on another thread.

That said - I've gotten the lowest MPG's ever (in 10K miles) on this last tank of fuel (I filled up right after I got the tires put on). I don't want to get into numbers but I did make a couple of shorter trips on this tank. I surmize that it is possible that in stop & go traffic, MPG's may suffer a little because of the added friction created by more traction and geting the larger tires to roll from a stop. I'm guessing at Hwy travel MPG's may increase slighty due to the reduction in RPM's. I used to run about 2300 RPM's at 70MPH, now I seem to run just slighty above 2000 RPM's at 70 MPH which is close to what my 5.3L 1500 with a 3:42 rear end used to run at (I know some wise-acre is going to figure out the exact reduction). More testing to come.....

Just thought I'd share the info.

Any pics at all.....im thinking about upgrading to some 265's for now....thanks....

I'll post a couple, maybe tonight if I can find the time between 3 kids baseball practices, daughters confirmation classes, Little League coach meeting......you get the idea :)

Out of curiosity, what kind of mileage are you getting?

I'll post a couple, maybe tonight if I can find the time between 3 kids baseball practices, daughters confirmation classes, Little League coach meeting......you get the idea :)
Yes I do. I'm down from 3 to 2 now and not coaching, just help out):h
Little league is one of the best things in the whole world:ro)

Just a personal observation from when I made the switch. I watch the EGT's real close when towing the fifth wheel and my the 265's cost me about a 75 degrees. I now get about 950-975 at 65mph. With 245's it was closer to 890. I still like the 265's but there is a noticeable difference.

What kind of tire pressure are you running?

What kind of tire pressure are you running?
55psi all around

Also I fueled up today and figured MPG's for this tank. I got 15.5 which wasn't as bad as I had initially thought it was going to be. The diff may have just been the amount of short trips done on this tank - so take the MPG's out of the equation for now.

Sounds right. I lost about 2 mpg after the switch (and correcting the miles). I NEED them for the load capacity, so I will live with it.

Did you have your speedo recaled? You need to take into account that you are actually going further than the odometer shows. I think there is like a 2.9% difference. That being said, your speedo is also reading slow too. If you are truely getting 15.5 mpg with 265s, that sucks because I am averaging a little over 16 mpg with 285s and aftermarket rims. Most my trips are less than 30 miles.

Not sure how it's accounted for but I'm assuming you took into account the larger circumference of 265 tire vs 245. If not accounted for, odometer will read 300 miles but with larger tires you actually travelled farther improving your mpg calculation. Probably not a big difference but when getting down to tenths of mpg....

What difference are people seeing going to 285?

Skoryaro2, I've got my hands full with a statistical analyst on the DP MPG thread. I can only handle one "super anal" person at a time. ):h Did you follow the DP MPG fill-up method? :D OK Habanero, JJ's coming back at ya! Later. :)

Did you have your speedo recaled? You need to take into account that you are actually going further than the odometer shows. I think there is like a 2.9% difference. That being said, your speedo is also reading slow too. If you are truely getting 15.5 mpg with 265s, that sucks because I am averaging a little over 16 mpg with 285s and aftermarket rims. Most my trips are less than 30 miles.

Sorry, I've been around this forum enought to know that I should have made mention that I recal'ed the speedo with my Predator and checked it against the GPS for accuracy.

Also, when I say "short trips" I'm talking several 3-4 mile trips to town and back per day being a kid-taxi. Unless I go on a road trip - my "longer trips" are 20 - 25 mile runs. Yet, another MPG variable.

I've reading this thread and learning a lot. The one thing I do know, is that a lot of these trucks are off on the speedo dept. I had my PCM tuned to work with 265 tires and ended up putting on 285's to find out that the 285's are dead balls accurate with a GPS.My city mileage can go anywhere from 11.2 to 11.8 mpg (gasser) depending if I use the GPS or I add the percentage difference. I also question the percentage for adustment because I know a lot of you guys who run 285's do it with the stock rims which imo makes the whole package a lot taller than the figures used to determine the percentages.
Man, who thought mileage can be so complicated?

:confuzeld Agreed on the OEM speedo being off. If I use the Predator to monitor my speed it is always within about .5 MPH of the GPS at all speeds. Compare the Predator & GPS with the OEM speedo and at times the OEM is the only one off. On my truck they all match at 70 but OEM is 2 MPH off at 60. They match again at 40 MPH

Gps isn't always accurate to the degree you think it is for cumulative mileage. Also the 245/265 difference is really 4% in diameter.

Last week I went from stock 245 tires to 265 Toyo's. A couple observations after about 325 miles on the new tires. Ride seems to be about the same, truck looks better, new tires are more square at the sidewall so the truck does not seem to corner as good as it did. I need a slight alignment adjustment but side to side tire sway seems to have increased. Much better traction. Slight tire noise going down the Hwy.

I'm pretty anal about tracking my MPG's and do it every tank and keep a running average. But please don't tell "JJ" (JJsDuMax) because I've been making fun of his DP MPG rules on another thread.

That said - I've gotten the lowest MPG's ever (in 10K miles) on this last tank of fuel (I filled up right after I got the tires put on). I don't want to get into numbers but I did make a couple of shorter trips on this tank. I surmize that it is possible that in stop & go traffic, MPG's may suffer a little because of the added friction created by more traction and geting the larger tires to roll from a stop. I'm guessing at Hwy travel MPG's may increase slighty due to the reduction in RPM's. I used to run about 2300 RPM's at 70MPH, now I seem to run just slighty above 2000 RPM's at 70 MPH which is close to what my 5.3L 1500 with a 3:42 rear end used to run at (I know some wise-acre is going to figure out the exact reduction). More testing to come.....

Just thought I'd share the info. With such a small tire change (difference is only 3.6 % in diameter) you should get 2217 RPM instead of 2300 RPM. I cannot image that this is noticalble at all in the MPG calculations, I would assume that MPG will increase and not decrease.

I too discovered the ~2MPG drop when I went from 245's to 265's. I discovered the stock speedo was reading too fast (on my truck) for the 245's since it was right on for the 265's w/o adjustment, hence the mileage I was getting before the 265's was BS (too high), distances were slightly further apart according to my odo, and warranty was eaten up just a little bit quicker...

Tim

"Gps isn't always accurate to the degree you think it is for cumulative mileage."

On the contrary everything I've read says GPS is one of the most accurate measuring tools in existence for speed and distance.

I just switched to 265's from 245's, I put on Michelin LTX M/S. The ride is rougher on bumpy country roads, on the way from the tire shop I pulled over and let the air down to 55lbs and it helped some. I like the look but haven't run enough miles to check mpg. Also there is a slight rub on the wheel well on full lock left turns.

:rolleyes: Just a thought here, but if everyone that talks about tire sizes would either put the overall diameter in inches or the full aspect ratio of say 285/75/16 instead of just saying 285s or 265s:secret:. The first number is the width of the tread, the second number is the persent of the first number from the rim to the tread on the sidewall, the third number is the rim width which you need to add to the tire sidewall hight to get total diameter,:think:. At any rate you could be running 33 inch tires in either 265s or 285s, one just wider than the other. This would help out ol JJ and the DP MPG formulas i think or at least keep down some of the questions on tire sizes.

skoryaro2, you thinking what I'm thinking? :D JJ

skoryaro2, you thinking what I'm thinking? :D JJ
I'm there!

LOL, what are yall thinking??I'm there!

With such a small tire change (difference is only 3.6 % in diameter) you should get 2217 RPM instead of 2300 RPM. I cannot image that this is noticalble at all in the MPG calculations, I would assume that MPG will increase and not decrease.

It appears that I lost 1/2 - 1 MPG in city driving since the increase in tire size. I can only surmize that it is because of the extra force that is required to get the tires rolling, which adds up after alot of stop & go city driving.

Haven't done a long road trip yet to compare Hwy. MPG's since the tire change.

ssduramax, we're thinking "You be anal to!" ):h We really should have a "DP Anal Club", this way the other members will know what they're dealing with when they reply to our posts. :D JJ :)

ssduramax, we're thinking "You be anal to!" ):h We really should have a "DP Anal Club", this way the other members will know what they're dealing with when they reply to our posts. :D JJ :)
:bounce: JJ, I would be :hail:honored to become a member :Handshakeof the "DPAC" (the army got me used to using acronyms...lol). which brings me to the "DP MPG Computation Method" name. As for that acronym, it needs tweeking, too hard to remember. Maybe DPCMMPG ?? what do you think?

Who'd ever thunk being anal could get you into a club, well maybe the debate club! :D Skoryaro2, this is your thread dude, I'll bounce the anal club idea with a new post. Da boyz are going to love this! Prepare to be made fun of JJ!:o: I'm used to it! ;)

It appears that I lost 1/2 - 1 MPG in city driving since the increase in tire size. I can only surmize that it is because of the extra force that is required to get the tires rolling, which adds up after alot of stop & go city driving.

Haven't done a long road trip yet to compare Hwy. MPG's since the tire change.

Will be doing about a 700 mile round trip all x-way this weekend hunting the ever elusive MI turkey. Should give me a good gauge as to any change in Hwy MPG's.

"Will be doing about a 700 mile round trip all x-way this weekend hunting the ever elusive MI turkey. Should give me a good gauge as to any change in Hwy MPG's."

Well? :confused: JJ :)

"Will be doing about a 700 mile round trip all x-way this weekend hunting the ever elusive MI turkey. Should give me a good gauge as to any change in Hwy MPG's."

Well? :confused: JJ :)

Well - without going into alot of detail I don't think this trip would have been a good MPG gauge, that's why I didn't report a follow-up.

Due to a late April 12" snow fall, rather than my trip being all x-way, many of my miles ended being cruising the backroads at 20 MPH trying to find a flock of turkeys that wanted to answer to my calling :)

Unofficially I'd say there was a MPG improvement, but I will take another road trip soon.

P.S. The turkey hunting was a bust! (Gobble! Gobble!)

Skoryaro2, I do my best hunting in the frozen food section! ):h BTW, are you a AAAA member yet? Cruise the LLY forum to gain more intel! JJ :)

Finding a flock in the Spring? Never tried that, but it works for me in the Fall. Spring time I'm doing crow and owl calls to get them gobbling on the roost before sun up, set up 100 yards away........ yelp yelp yelp....purr..... BANG!

Finding a flock in the Spring? Never tried that, but it works for me in the Fall. Spring time I'm doing crow and owl calls to get them gobbling on the roost before sun up, set up 100 yards away........ yelp yelp yelp....purr..... BANG!


FYI - I do both, shock call and find the flock to find figure aout where they are roosting at night AKA "putting them to bed" :)

Will be doing about a 700 mile round trip all x-way this weekend hunting the ever elusive MI turkey. Should give me a good gauge as to any change in Hwy MPG's.


Finally did a road trip yesterday to get some decent numbers to compare MPG's since the new 265 tires replaced the stock 245'. Tried to follow the "DP MPG Rules" as much as possible.

About 400 miles mostly flat, some minor grades. All Hwy. First 200 was pulling a 6K camper and the bed of the truck was FILLED with firewood = 12.2 MPG at 70MPH.

Second 200 miles (return trip same route) was completely unloaded - not towing= 19.2 MPG at 72 MPH.

All hand calculated and I was sure of my tank refills (used a modified dipstick). I also just turned over 12K on the speedo.

MY conclusion after sometime driving now with the new tires: Change in tire size created 1/2 MPG to no loss of MPG's in city driving. Hwy driving saw in increase of 1.5 - 2.0 MPG's. I couldn't get close to 19 with the 245's. Best I ever did was just over 18 MPG on the Hwy (basically the same route as this test) and that was at about 5 MPH less than I travelled this time.

FWIW

Rob

CAUTION: "Quad A" Response

What were the outside temperatures during these runs? With the onset of warmer temperatures we should expect an increase in mpg's. Need to rule that out as a factor! JJ :)

CAUTION: "Quad A" Response

What were the outside temperatures during these runs? With the onset of warmer temperatures we should expect an increase in mpg's. Need to rule that out as a factor! JJ :)

37F in the AM run - 48F on the return (with an occassional rain shower ;))

On a side note: Has anyone ever noticed that their exhaust smells different on summer and winter fuel? Why do I ask?

When I first got my truck last September 28 I noticed that the exhaust had a "sweet" smell to it and less of a diesel smell. I blamed it on the Stanadyne. Around the end of October I quit using Stanadyne and went to Power Service and the smell changed to a deisel fuel smell. Yesterday I noticed the exhaust smelled "sweet" again for the first time since October, and I'm still using Power Service. I wonder if it is actually the different smell of winter and summer fuel and I just got my first tank of summer fuel?

If so, that could be a MPG factor too!

Finally did a road trip yesterday to get some decent numbers to compare MPG's since the new 265 tires replaced the stock 245'. Tried to follow the "DP MPG Rules" as much as possible.

About 400 miles mostly flat, some minor grades. All Hwy. First 200 was pulling a 6K camper and the bed of the truck was FILLED with firewood = 12.2 MPG at 70MPH.

Second 200 miles (return trip same route) was completely unloaded - not towing= 19.2 MPG at 72 MPH.

All hand calculated and I was sure of my tank refills (used a modified dipstick). I also just turned over 12K on the speedo.

MY conclusion after sometime driving now with the new tires: Change in tire size created 1/2 MPG to no loss of MPG's in city driving. Hwy driving saw in increase of 1.5 - 2.0 MPG's. I couldn't get close to 19 with the 245's. Best I ever did was just over 18 MPG on the Hwy (basically the same route as this test) and that was at about 5 MPH less than I travelled this time.

FWIW

Rob


Don't know how accurate of a test the above was. Just refilled today after a week of my usual drive pattern to and from work and saw an increase of 1+ MPG's above what I usually get.

I'd have to say summer fuel has kicked in just as I was trying to monitor MPG's after my tire size change. :confuzeld