MPG on 33in/285s

My Speedometer is consistently slower I would say by 6-7 MPH now (according to GPS and radar) since switching to 33s. Have not used the Dakota Digital to attempt to correct it either. As for mileage, pfft... with the speedometer and odometer now off - who really knows. Its definitely not a Camry LE.

 

I wouldn’t worry about it til you regear. It gets wayyyyy off after a regear.

 

I daily drive my truck with 4.10 and 33s gas is pretty good also have a economy tune and alloy wheels also have ATs to be specific I have general grabber atx

 

An E rated 255/85 is STILL lighter than a E rated fatty.

Even so, I'm not sure why you'd want a C rated off-road tire, however. If you're traveling over terrain that is rough enough to need a mud terrain, it's likely rough enough to destroy a C rated tire, plus they don't handle lower pressures as well either because the sidewall is so thin.

 

The ECU readings really aren't a great way to calculate mileage. The only "real" way is to divide your # miles driven by the # gallons you put in at the gas pump. My '17 4Runner has always read at least 1 mpg or 2 high.

 

So you get better than the EPA estimated mileage of a stock truck with your 33" M/Ts?

 

I think it's a trade-off, really. Essentially, you trade (in my opinion)

ride comfort 100% of the time
less wear-and-tear on suspension, steering, and drive train
"more power" due to lighter tires (which are unsprung, and so the "worst" kind of weight)

vs.​

robustness of tire (fewer flats)​

I will say that I definitely got more flats when running the Duratracs vs. my ST Maxx now, but there was a lot to like about the C-load. At least in the crowd I run around with, we're all always looking for a nice ~33" C-load tire...though I think we're all running E's with the exception of a 35" (on 15" rims) that's C.

 

It's not just about flats. You can air down to a lower PSI and still hold the bead, and the sidewall won't collapse under the reduced pressure. That means more available traction.

Of course, you will *always* make compromises when you have a truck that has to serve 2 (or more) functions. That said, I have E rated 265/75 KO's and the ride is perfectly fine (I don't expect it to ride like a Cadillac, lol), and I've *never* gotten a flat (on or off road) in 15 years of owning this truck with these tires (2 sets).

Now that it's a trail truck and not driven daily, I care even less about the mpgs. I've even considered not carrying a spare when I get my 33's, although I probably won't...

Just for fun, let's compare weights of a 285/75 in a D range (I couldn't really find a comparable C range) to a E range 255/85:

Nitto Grappler A/T 285/75 (not quire a 33") = 54 pounds

BFG KM3 255/85 (over 33") = 59 pounds.

If you collect precise enough data for the additional 20 pounds to be statistically significant to your mpg's, you're more of a data nerd than I am (and I'm a geophysicist).

 

What's weird is that I haven't noticed this at all with my truck, granted I haven't used GPS to get an exact reading but every single time I pass by a radar detector it's always spot on with what my speedometer says. I know our gauges only go in increments of 5 so they aren't very exact but it almost seems like I'm only off by 1 or 2mph or so if that.

Of course it could just be the inaccuracies of those radar detectors, I really should try and track it with GPS sometime.

But yeah whenever mileage talk comes up I just throw out '15mpg' because I know it's somewhere around there, and I don't really want to think about it too much because it depresses me with how high gas prices are in CA lol.

 

I'm on 285/75/16 MTs and leveled and I average 17.5 per tank. I keep the RPMs under 3k when possible and drive 65-70 on the highway. I also do a solid 7-8 miles of hill driving each day because my house is located in that area.

 

If you're on Android, try Waze. It'll give you your speed as tracked via GPS by the app.

 

My phone's GPS is fucked, rarely works the way it should I have to use directions on Google Maps as though I were reading them off of Mapquest haha. Hasn't really bothered me though, but it's about high time I got a new phone anyway.

 

All this talk about MPG but everyone leaves out their truck configuration so it’s like comparing apples and oranges.

Single, xtra, double cab
Manual or auto
4x4 and non 4x4
Miscellaneous - armor, winch, camper, lift etc

All that play a big role in what your truck would average.

For everyone that gets 17+ mpg

 

03 DC V6 auto, full OME lift, 255/85R16 E range MTs, full skids, sliders, ARB with winch. Just did a trip from Denver to SE Utah and back, got right around 17 mpg. I'm not regeared, so I struggle maintaining over 70+ mph over 9000 feet, so I tend to cruse at 60 to 65. Speeds are from GPS, speedo reads ~4-6 mph low on the highway.

 

Best MPG I've ever gotten was averaging 18mpg from Sacramento, to northern Washington and back. That was because I was towing this little Coleman popup trailer that weighed like 800 pounds. Truck didn't notice the weight, but it was fairly unstable so I couldn't go over 55.

 

How are you liking them? I'm debating getting some 255s for some more clearance. Although I've always ran bfg without issues so also debating staying or leaving bfg.. all the bros raising prices

 

I have a extra cab 1998, 3.4L SC, 3" lift and 33's and i would say average of 15 is accurate. i do alot of backroading and off roading so that will cut you back alot creepin around in 4WD. But highway i would say 15MPG or so is spot on.

 

33x12.5x15 Crosswind M/T weigh about 54lbs a piece

 

I love them, well worth the upgrade. 255s are a 'true' 33" tire at 33.1"...285s are 32.something. Only thing is it takes some work to make them fit right, some trimming will be required...more or less depending on your wheels and backspacing. Also important to have your lower caster settings at ~3 degrees, once I finally got that it completely eliminated all my rubbing issues with the 255s. I just had to flatten the pinch weld which is pretty common to do.

There are pretty limited options though in 16in 255s...Cooper has a couple, the STMaxx are probably the most popular followed by the BFG KM2 M/Ts.

There are more options if you consider the lesser known brands.

 

OK, we're getting in the weeds here but if we're going full nerd (I was on - and ran - the Excel team for 19 years), I'd say your proving my point . In fact, even you said at the beginning of the thread that bigger tires are going to cause the largest MPG loss; that's because of the extra weight, not because of the size (for the most part).

Back to the data:

At 285/75/16 is 11.2" wide vs a 255/85/16 which is only 10" wide. And D's are already going to be heavier than C's, so let's find a better comparison.

Let's take 265/75/16 - that's a size where we can find a C and E of the same tire:

• Wrangler DuraTrac - Off Road/Mud Terrain | (LT)112Q C - 45 lbs
• Wrangler DuraTrac - Off Road/Mud Terrain | (LT)123Q E - 51 lbs

OK, so we're looking at a 6 lbs difference - or 6/45*100%=~13% increase in weight, at least for Goodyear. So really, we're looking at a difference of 51 vs 58 lbs if we look at a similar ratio for a 255/85/16 ST Maxx.

28 lbs of unsprung weight is like running another half a tire. Plus, it's unsprung, so it's not like putting 28 lbs in the passenger seat; it takes a lot of energy to get (and keep) that extra 28 lbs rotating.