Math deficiency: Talk to me about calculating mileage with non-stock tires

I'm on 33's so I'm guessing that's closer to 7%.

 

works to the extent when driving at hi-way speeds

the tyres crown............they grow in circumference

this truly a starbux conversation = to mine is bigger than urz

if U calculate in an effort of trip planning

miles & gallons.....................U cant be wrong

no one in their right mind is goin to stop 3% shorter than their destination

or run out o fuel 3% short o fill up when Uv passed a dozen stations

 

?

 

genius !!!!

 

IDK, if 31's are stock, and 32's are 3.4% larger, I figured 33's would be 6.8% larger. I'm a moron though.

 

Eh, I'm just trying to help with the question of HOW you calculate it, not WHY anyone would care to. But someone with much larger tires going by what their trip computer shows might say "I only get 14 MPG now" when they are actually getting 15 MPG. I have the same size difference as OP (my calculation was 3.29% difference), and my truck regularly shows 16.5 MPG. But I know I am actually getting 17. I don't use that to calculate fuel for a trip, though -- wind, elevation, traffice conditions, and fits of road rage can change things pretty quickly.

 

The best method is to not care. It's a freaking heavy duty truck, with heavy duty suspension, and strong tires so you will not be getting awesome numbers anyway.

 

I think your equation on the first page was what OP was looking for. That's the method I use as well and I keep track of it in Fuelly. We are planning a cross country trip this summer, so I'm already plotting out fuel stops.

 

FUEL UP


TIRES GO BOOM

MILES COUNT ONCE

DONT MAKE ME NO NEVERMIND

POKEMON AND CHARAZARD

FUEL MILAGE

 

This is why I should stay out of the 3rd gen forums.

 

its all n Ur head

Ur goin to stop when U have to.....................

1 mpg could realisticaly be attributed to driving habits................... terrain.................. traffic

the argument im sitting on the shoulder NO FUEL ...................i should have been able to go 6 more miles

therapy costs more

 

The responsible vehicle owner always verifies the accuracy of the vehicle's odometer vs GPS acquired data during the early stages of ownership and following any modifications that could affect that accuracy. Using the odometer readings for calculations without having done this only presents questionable results.

My Tacoma travels 3% further than the odometer indicates.

 

responsible for a few miles 3% represents
obsessive
analytical retentive

i travel a lot crossing the usa
not unusaul getting 400 miles / tankful........................3% to worry about 12 gallons
not worth the ulcer

as i mentioned b4 as some are want to disregard

same truck same size tyres NEW...................to worn down to legal wl be close to that 3% at least
tyre wear
speedo error
tho the 5th generation GPS is more accurate...............sometimes not
( ez to believe in the easter bunny.....great pumpkin ......santa........tooth fairy)

 

Just break out the Chains. No need if you broke the Plane.

 

Best option: zero your trip meter and drive a long ways with an accurate gps. Minimum 100 miles, that makes the math easy. Whatever the GPS says you actually went divided by your trip meter reading is your conversion factor.

Example: GPS says you went 110 miles, trip meter says 100. 110/100=1.1. This is what you multiply your trip meter reading at any given distance to get adjusted mileage. Divide that by amount of gas put in at the pump and you get MPG.

 

I appreciate all of the responses. I'm certainly not doing this for trip planning, its just that this Tacoma is new to me and the MPG has been much less than I expected. Like 14 mpg on the highway at 75mph and 16 in town with mixed conditions. My '08 FJ got 17 in town and about 21 on the highway, so this has been a disappointing surprise.

I'm going to be getting a tune to the ECU at the end of the month and I'm trying to get a reasonably accurate sense of what kind of mileage I'm actually getting now vs. what I'll be getting. I get that there are a bunch of variables but even a half a mile per gallon more due to a calculation error is welcome news.

 

‘ tuning the ECU ‘ ......................

‘ tuning ‘ usually results in more power = less MPG

no doubt a ‘ tune up ‘ could be leaned out a bit more than the already ‘ lean ‘ EPA requirement

the MPG could improve with further break in miles & some conservative driving

I have an Stock SR 2.7/4 auto can get 400-450 miles per tank when traveling ( toothbrush underwear & sox )

 

I find Road Dog’s posts simply delightful....almost like learning challenged Haiku. In my mind, I read them as such.

Mods, can we make him the Poet Laureate of TW?

 

A larger diameter tire will make fewer revolutions per mile.

The MILE counter on the truck counts revolutions.

So, a bigger tire will show fewer miles.

For the math, for your set up......

MPG = (1.034)*(miles on trip set)/gallons at fill up

BTW, your speed will be off by the same amount. The speedometer will report a slower speed than actual.

One more point. Speeds above 70 mph kills the fuel efficiency. You'll do better sitting in the RH lane running <70mph.

 

It's like some weird Tacoma Fortune Cookie. If he starts listing lucky numbers, imma lose it.