Toyota Nation Forum banner
1 - 20 of 23 Posts

·
Registered
My 05 Tacoma PreRunn
Joined
·
26 Posts
Discussion Starter · #1 ·
So i recently upgraded from dunflops to Firestone destination A/T's. Also upsized to a 265/70/17 (from sport rims stock size) and my mpg just sank. I was getting 18 to 19 mpg and now 15-16. No real change in driving conditions.

Here are some of my truck stats: 05 prerunner access cab off road edition. Stock engine, flowmaster dual catback exhaust. Sport rim swap.

I figured I would lose some mpg but not this much. The tires are the obvious reason to this but damn, anything I can do besides take the tires back? Should I switch to destination L/E's?
From what i can tell there are no other reasons...oil is fresh/intake clean/no rubbing/no recent brake work. Another thing i just thought of is they did an alignment which is still pulls to the right a little..


Any advice (besides suck it up)?

THanks
 

·
Premium Member
08' Tacoma Dbl Cab
Joined
·
5,556 Posts
I installed a Hypertech Calibrator because I was too lazy to do the extra math, and I wanted the miles on my odometer to be accurate for service and value purposes.

The equation required to figure out the percentage your odometer is off is as follows:

The 265/65/17 tire makes 660 rev/mile, the 265/70/17 tire makes 638 rev/mile.

660 minus 638 = 22

22 divided by 660 = 3.33 percent

So your speedo, odo, and tripmeter are all slow by 3.33 percent. If you don't want to spend the money to install a calibrator (~$200), then to compute accurate fuel mileage, you need to add 3.33 percent to the miles indicated by your tripmeter.

Example:

19.0 gallons of fuel

330.0 miles per tripmeter + 3.33% = 340.9 miles

340.9 miles divided by 19.0 gallons = 17.94 MPG
 

·
Registered
Joined
·
226 Posts
I thought that the bigger the tire the less the rev/mile or am I wrong ? I compare it to a chiwawa and a greyhound. The chhwawa (small tire) takes more steps to cover the mile than the greyhound (big tire). Am I missing something here?
 

·
Registered
Joined
·
226 Posts
So i recently upgraded from dunflops to Firestone destination A/T's. Also upsized to a 265/70/17 (from sport rims stock size) and my mpg just sank. I was getting 18 to 19 mpg and now 15-16. No real change in driving conditions.

Here are some of my truck stats: 05 prerunner access cab off road edition. Stock engine, flowmaster dual catback exhaust. Sport rim swap.

I figured I would lose some mpg but not this much. The tires are the obvious reason to this but damn, anything I can do besides take the tires back? Should I switch to destination L/E's?
From what i can tell there are no other reasons...oil is fresh/intake clean/no rubbing/no recent brake work. Another thing i just thought of is they did an alignment which is still pulls to the right a little..


Any advice (besides suck it up)?

THanks
Did you get a P(passenger) rated tire or go hardcore and get a C or D ?
 

·
Registered
My 05 Tacoma PreRunn
Joined
·
26 Posts
Discussion Starter · #9 ·
Didn't choose c or d and there are no markings stating either. 113S M+S etc etc. No p,c,d rating markings that i see?
 

·
Registered
04CobraCBR95408Tac
Joined
·
77 Posts
Wow this thread looks kind of familiar.. :)

Does or can the dealership correct the tire offset btw??? Reason I ask is I know my friend who has a chevy the dealership was able to recalibrate this odometer/speedometer for a small fee. (wasn't expensive)

Now I'm 2nd guessing adding the 265/70 series tires onto my truck..
 

·
Registered
04CobraCBR95408Tac
Joined
·
77 Posts
OK I may start a new thread after some research.. I'm not doubting you 08TRDOffRoad

However I had to call dealership in regards to if they have the ability to recalibrate the odometer. (They do not) SVC tech I spoke to actually brought up chevy's and how they are able to do it.

HOWEVER they did say that the odometer runns off of the speedomenter and if the speedo is wrong the odometer will be wrong. Well going UP in tiresize will correct my speedometer and probably read the RIGHT MPH.

FYI I'll be starting a new thread this afternoon possibly.. (after research and that 'search' button)
 

·
Premium Member
Was a 05 Tacoma 4x4 DC LB
Joined
·
13,029 Posts
OK I may start a new thread after some research.. I'm not doubting you 08TRDOffRoad

However I had to call dealership in regards to if they have the ability to recalibrate the odometer. (They do not) SVC tech I spoke to actually brought up chevy's and how they are able to do it.

HOWEVER they did say that the odometer runns off of the speedomenter and if the speedo is wrong the odometer will be wrong. Well going UP in tiresize will correct my speedometer and probably read the RIGHT MPH.

FYI I'll be starting a new thread this afternoon possibly.. (after research and that 'search' button)
Well right off the bat you got bad information from the dealership. They stated "if the speedo is wrong, then the odo is wrong." If that were the case, then toyota would be sued just like Honda was. With stock tires, when the speedo reads 65, you're actually doing only 61. But the odo is accurate. Upsizing to the next tire size up (going from 265/70-16 to 265/75-16 or from 270/65-17 to 270/70-17) usually fixes the speedometer to be almost dead on at those speeds, but then the odo reads less miles than actually traveled. So don't trust what the dealership says. They were correct, however, in saying they couldn't just go into your truck and adjust the speedo to be accurate. Thus the need to purchase aftermarket products to do that (and I believe those only became available just a couple of years ago??).
 

·
Registered
My 05 Tacoma PreRunn
Joined
·
26 Posts
Discussion Starter · #14 ·
OK I may start a new thread after some research.. I'm not doubting you 08TRDOffRoad

However I had to call dealership in regards to if they have the ability to recalibrate the odometer. (They do not) SVC tech I spoke to actually brought up chevy's and how they are able to do it.

HOWEVER they did say that the odometer runns off of the speedomenter and if the speedo is wrong the odometer will be wrong. Well going UP in tiresize will correct my speedometer and probably read the RIGHT MPH.

FYI I'll be starting a new thread this afternoon possibly.. (after research and that 'search' button)
There's a search button?:clap::clap::clap:
 

·
Registered
04CobraCBR95408Tac
Joined
·
77 Posts
Upsizing to the next tire size up (going from 265/70-16 to 265/75-16 or from 270/65-17 to 270/70-17) usually fixes the speedometer to be almost dead on at those speeds, but then the odo reads less miles than actually traveled.
Cool thanks.. After reading the above information some reason I was thinking the odo was reading MORE miles then actually traveled but then the title of this post would be reading an INCREASE in MPG. (when upsizing in tires)

Sorry hope I didn't hijack the thread to bad here..
 

·
Registered
14 Tacoma
Joined
·
207 Posts
So i recently upgraded from dunflops to Firestone destination A/T's. Also upsized to a 265/70/17 (from sport rims stock size) and my mpg just sank. I was getting 18 to 19 mpg and now 15-16. No real change in driving conditions.
...Should I switch to destination L/E's?...
Destination LE's are on-road use only. Very smooth ride & excellent wear, best factory supplied tires I ever had.
 

·
Premium Member
08' Tacoma Dbl Cab
Joined
·
5,556 Posts
Well right off the bat you got bad information from the dealership. They stated "if the speedo is wrong, then the odo is wrong." If that were the case, then toyota would be sued just like Honda was. With stock tires, when the speedo reads 65, you're actually doing only 61. But the odo is accurate. Upsizing to the next tire size up (going from 265/70-16 to 265/75-16 or from 270/65-17 to 270/70-17) usually fixes the speedometer to be almost dead on at those speeds, but then the odo reads less miles than actually traveled. So don't trust what the dealership says. They were correct, however, in saying they couldn't just go into your truck and adjust the speedo to be accurate. Thus the need to purchase aftermarket products to do that (and I believe those only became available just a couple of years ago??).
Thank you!!!! Moral of the story is, dealerships are full of crap 95% of the time....:headbang:

You are correct I think the Hypertech Calibrator has only been available for a couple of years now. I read somewhere of another....cheaper option as opposed to the hypertech. I can't remember all the info tho.

With the larger tire and the hypertech my odometer is dead on and my speedo is more accurate than it was from the factory!

Now back to the OP, what is your fuel mileage after using the correct equation to figure it???
 

·
Registered
My 05 Tacoma PreRunn
Joined
·
26 Posts
Discussion Starter · #18 ·
Should be filling up later today and ill post the mpg tonite.

Cannot find hypertech for 05.....says unavailable from their "supported sellers" ??

Thanks
 

·
lover of teh boobies
'05 Tacoma AccessCab
Joined
·
2,547 Posts
Should be filling up later today and ill post the mpg tonite.

Cannot find hypertech for 05.....says unavailable from their "supported sellers" ??

Thanks
Funny, worked for me just fine. To be honest though, the Hypertech has only gotten success stories from people with Automatics. The 6 speed users that have tried it.. it hasn't worked properly.
I have, however seen great results accross the board with the Dakota Digital speedo cal.
http://www.dakotadigital.com/index....tegory_id=287/home_id=59/mode=prod/prd126.htm
 

·
Registered
My 05 Tacoma PreRunn
Joined
·
26 Posts
Discussion Starter · #20 ·
1 - 20 of 23 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top