Ford Ranger Forum - Forums for Ford Ranger enthusiasts!

Go Back   Ford Ranger Forum - Forums for Ford Ranger enthusiasts! > >
Forgot Password? Join Us!

Welcome to Ford Ranger Forum

Reply
 
Thread Tools Search this Thread

  #1  
Old 11-26-2014, 07:04 AM
Hlifted Ranger Hlifted Ranger is offline
Liking the Ford Ranger Forum
 
Join Date: Nov 2014
Posts: 23
Default Bigger Tires & Speedometer

Hey, I got my truck lifted on 33s and am wondering if the bigger tires would affect the speedometer or OBDII reader?

Reason I'm asking is cause someone said I may have to get it calibrated or it wont show the correct speed, but I really don't think I'm going any faster then what its telling me. I was more concerned about the OBDII reader, since it is telling me I get ~23-24mpg when driving to work through the country roads, which seems too good considering I got a lift, bigger tires, and heavier front bumper then stock. Any one have any ideas if the tires would affect MPG readings?
__________________
2011 Ford Ranger FX4 Sport:
|3'' Body Lift + Leveling Kit|Custom Built Off-Road Front Bumper|BF Goodrich All-Terrain Tires|Sony Stereo|10" Comp Sub|Non-existent Muffler|Knock-off Magnaflow Exhaust|
Reply With Quote
  #2  
Old 11-26-2014, 07:32 AM
Logan03CO Logan03CO is offline
No wire hangers, ever!

 
Join Date: Jun 2010
Posts: 10,365
Default Re: Bigger Tires & Speedometer

Quote:
Originally Posted by Hlifted Ranger View Post
Hey, I got my truck lifted on 33s and am wondering if the bigger tires would affect the speedometer or OBDII reader?
Yep.

Larger and/or smaller tires will effect both the speedometer & odometer which in turn will effect any calculation that uses either (MPG's etc.).

How much depends on the overall circumference change.

Random Example:
'Before' Tire Size = 255/70/16
'After' Tire Size = 33x12.5x15's

Speedometer Reading (mph) = 50
Actual Speed (mph) = 54.9
__________________
Curent 2003 Ford Mustang Mach 1 owner - Build Thread for her: Logan's 2003 Mach 1

Former 2003 Ford Ranger owner - Build Thread for her: Project Budget Buster

Last edited by Logan03CO; 11-26-2014 at 07:36 AM.
Reply With Quote
  #3  
Old 11-26-2014, 05:11 PM
Hlifted Ranger Hlifted Ranger is offline
Liking the Ford Ranger Forum
 
Join Date: Nov 2014
Posts: 23
Default Re: Bigger Tires & Speedometer

O dang, I swear Im not going any faster cause I matched the speed of a school bus on the highway going 115kph, according to your calc he wouldve been going almost 125kph... guess he was roasting lol!

Do you know how to calibrate it at all or is there a way to confirm?
__________________
2011 Ford Ranger FX4 Sport:
|3'' Body Lift + Leveling Kit|Custom Built Off-Road Front Bumper|BF Goodrich All-Terrain Tires|Sony Stereo|10" Comp Sub|Non-existent Muffler|Knock-off Magnaflow Exhaust|
Reply With Quote
  #4  
Old 11-26-2014, 06:51 PM
Logan03CO Logan03CO is offline
No wire hangers, ever!

 
Join Date: Jun 2010
Posts: 10,365
Default

Quote:
Originally Posted by Hlifted Ranger View Post
Do you know how to calibrate it
Most use a tuner like the SCT X4 or Flashpaq.

Plus, you'll get a bit of increased power at the same time.

Quote:
Originally Posted by Hlifted Ranger View Post
is there a way to confirm?
Consider it confirmed....anytime you change tire sizes - the vehicles displayed speed is effected.

If it's enough to notice....depends on the speed you're going and the amount of increased tire size you're dealing with.

That's why they have a million 'tire size vs. speed conversion calculators' online.

Your truck doesn't use GPS to calculate speed or anything. Its all based on a fixed 'rotation per mile' setting in the PCM. The truck has no clue as to the size tire you're running without you telling it so.

Unless your factory speedo was on the slow end of the scale prior to changing tires.....you should notice the difference when going to 33's from a stock tire size.



Shot in the dark - but did you buy it used with the 33's already on it by chance?
__________________
Curent 2003 Ford Mustang Mach 1 owner - Build Thread for her: Logan's 2003 Mach 1

Former 2003 Ford Ranger owner - Build Thread for her: Project Budget Buster

Last edited by Logan03CO; 11-26-2014 at 07:06 PM.
Reply With Quote
  #5  
Old 11-27-2014, 09:34 AM
Hlifted Ranger Hlifted Ranger is offline
Liking the Ford Ranger Forum
 
Join Date: Nov 2014
Posts: 23
Default Re: Bigger Tires & Speedometer

Quote:
Originally Posted by Logan03CO View Post
Shot in the dark - but did you buy it used with the 33's already on it by chance?
Nah man, I put those on after. I just had the stock tires that came with the truck. Could I get someone to calibrate the computer for me? Like an everyday mechanic or nah?
__________________
2011 Ford Ranger FX4 Sport:
|3'' Body Lift + Leveling Kit|Custom Built Off-Road Front Bumper|BF Goodrich All-Terrain Tires|Sony Stereo|10" Comp Sub|Non-existent Muffler|Knock-off Magnaflow Exhaust|
Reply With Quote
  #6  
Old 11-27-2014, 09:40 AM
Logan03CO Logan03CO is offline
No wire hangers, ever!

 
Join Date: Jun 2010
Posts: 10,365
Default Re: Bigger Tires & Speedometer

Quote:
Originally Posted by Hlifted Ranger View Post
Nah man, I put those on after. I just had the stock tires that came with the truck. Could I get someone to calibrate the computer for me? Like an everyday mechanic or nah?
Might be able to get it done at the Ford dealer - depending on size. Some people have said they are limited to the factory tire sizes that ever came on a Ranger...but I dont have any 1st hand experience with the Ford dealer doing it and the software they would use.

98% of people that change it get a tuner to do it.

If the dealer were to do it - I assume it would run an easy $100-150.
__________________
Curent 2003 Ford Mustang Mach 1 owner - Build Thread for her: Logan's 2003 Mach 1

Former 2003 Ford Ranger owner - Build Thread for her: Project Budget Buster

Last edited by Logan03CO; 11-27-2014 at 09:44 AM.
Reply With Quote
  #7  
Old 11-27-2014, 09:52 AM
camodown camodown is offline
I'm kind of a big deal
 
Join Date: Nov 2009
Posts: 4,849
Default

You can go up to 31" tires from a dealer since that is the biggest is came on a ranger. Then if you don't know someone they will charge you a minimum which is $100 or better depending on the dealership.

Might as well buy a tuner.
__________________
Lifted and junk

Double Lifted Rangers
Reply With Quote
  #8  
Old 11-27-2014, 02:06 PM
Hlifted Ranger Hlifted Ranger is offline
Liking the Ford Ranger Forum
 
Join Date: Nov 2014
Posts: 23
Default Re: Bigger Tires & Speedometer

Quote:
Originally Posted by camodown View Post
they will charge you a minimum which is $100 or better depending on the dealership.

Might as well buy a tuner.
Damn! I just bought a Scangauge on kijiji... Figured 24mpg was too good to be true lol
__________________
2011 Ford Ranger FX4 Sport:
|3'' Body Lift + Leveling Kit|Custom Built Off-Road Front Bumper|BF Goodrich All-Terrain Tires|Sony Stereo|10" Comp Sub|Non-existent Muffler|Knock-off Magnaflow Exhaust|
Reply With Quote
  #9  
Old 11-27-2014, 02:26 PM
Hlifted Ranger Hlifted Ranger is offline
Liking the Ford Ranger Forum
 
Join Date: Nov 2014
Posts: 23
Default Re: Bigger Tires & Speedometer

Quote:
Originally Posted by Logan03CO View Post
Yep.
Larger and/or smaller tires will effect both the speedometer & odometer which in turn will effect any calculation that uses either (MPG's etc.).
Hmmm, so my mileage is off too?

I guess I can see if it's off by measuring how far my commute is from work and then verify with google maps.

Sorry I keep asking, its just hard for me to believe that every time I go 120 kph, I'm actually going like 130 lmaooo, but yea prob gonna end up getting tuner soon anyway
__________________
2011 Ford Ranger FX4 Sport:
|3'' Body Lift + Leveling Kit|Custom Built Off-Road Front Bumper|BF Goodrich All-Terrain Tires|Sony Stereo|10" Comp Sub|Non-existent Muffler|Knock-off Magnaflow Exhaust|
Reply With Quote
  #10  
Old 11-27-2014, 03:48 PM
Logan03CO Logan03CO is offline
No wire hangers, ever!

 
Join Date: Jun 2010
Posts: 10,365
Default

You're not the first person to lift their Ranger.

It's been done one or twice before.....
__________________
Curent 2003 Ford Mustang Mach 1 owner - Build Thread for her: Logan's 2003 Mach 1

Former 2003 Ford Ranger owner - Build Thread for her: Project Budget Buster
Reply With Quote
  #11  
Old 11-28-2014, 07:50 AM
Hlifted Ranger Hlifted Ranger is offline
Liking the Ford Ranger Forum
 
Join Date: Nov 2014
Posts: 23
Default Re: Bigger Tires & Speedometer

Quote:
Originally Posted by Logan03CO View Post
You're not the first person to lift their Ranger.

It's been done one or twice before.....
wait WHAT??? ...I legit thought I was the only one lol
__________________
2011 Ford Ranger FX4 Sport:
|3'' Body Lift + Leveling Kit|Custom Built Off-Road Front Bumper|BF Goodrich All-Terrain Tires|Sony Stereo|10" Comp Sub|Non-existent Muffler|Knock-off Magnaflow Exhaust|
Reply With Quote
  #12  
Old 11-28-2014, 08:23 AM
Prages Prages is offline
Ford Ranger Driver
 
Join Date: Nov 2012
Posts: 1,574
Default Re: Bigger Tires & Speedometer

Think about it like this.

The circumference of a tire is it's diameter times pi (3.14159265)

So if your stock tires were 29" tall, their circumference was 91.106". That means that every time the axle rotated, you moved forward 91.106".

33" inch tires have a circumference of 103.672". Now, with 33" tires, you're moving forward 103.672" for every rotation of the axle.

Your speed sensor isn't measuring how far you're actually going forward, it's measuring how many times either the axle or transmission is rotating, and then assuming that each rotation is 91.106", but with the bigger tires, you're really going 103.672"

So you're really going almost 14% faster. So, when your speedo is saying 55, you're really doing about 62.
__________________
2000 Ford Ranger XLT
Extended Cab
3.0 Flex
4x4
Manual Transmission
Offroad Package
Reply With Quote
  #13  
Old 11-28-2014, 08:43 AM
Hlifted Ranger Hlifted Ranger is offline
Liking the Ford Ranger Forum
 
Join Date: Nov 2014
Posts: 23
Default Re: Bigger Tires & Speedometer

Quote:
Originally Posted by Prages View Post
So you're really going almost 14% faster. So, when your speedo is saying 55, you're really doing about 62.
I'm pretty sure my stock tires size was 255/70R16, so I don't think it would be as drastic of a difference. I measured my route from work the other day and the odometer was showing a distance of 51.9km but on google maps the route measured 54.2km, so it is off for sure.

Last question though regarding the odometer and mpg calculations. On my scangauge it is showing mpg of 24, which is obviously better then what it actually is. But if my odometer is telling me I'm actually driving LESS per tank, then wouldn't the MPG calculations be WORSE (like 13mpg) not better??

Either way I'm gonna end up buying a tuner in the near future to solve all this, but im just curious
__________________
2011 Ford Ranger FX4 Sport:
|3'' Body Lift + Leveling Kit|Custom Built Off-Road Front Bumper|BF Goodrich All-Terrain Tires|Sony Stereo|10" Comp Sub|Non-existent Muffler|Knock-off Magnaflow Exhaust|
Reply With Quote
  #14  
Old 11-28-2014, 08:55 AM
Vogenitz69 Vogenitz69 is offline
Ford Ranger Driver
 
Join Date: Nov 2012
Posts: 3,164
Default

Quote:
Originally Posted by Hlifted Ranger View Post
I'm pretty sure my stock tires size was 255/70R16, so I don't think it would be as drastic of a difference. I measured my route from work the other day and the odometer was showing a distance of 51.9km but on google maps the route measured 54.2km, so it is off for sure. Last question though regarding the odometer and mpg calculations. On my scangauge it is showing mpg of 24, which is obviously better then what it actually is. But if my odometer is telling me I'm actually driving LESS per tank, then wouldn't the MPG calculations be WORSE (like 13mpg) not better?? Either way I'm gonna end up buying a tuner in the near future to solve all this, but im just curious
your odometer is assuming that you are traveling the distance of stock tires. If the new tires are larger and spin more per rotation, your car is actually traveling 14% farther than what the odometer reads
__________________
2000 Ford Ranger XLT 2WD ~ Work-In-Progress: 5.0 V8, M5R2 5 Speed, 4" Suspension Lift, 3" Body Lift, 33" BFG's, Bilstein 5100's, Comp Cams XE258HR-12, 24# Injectors, Torque Monster Headers, Flowmaster 70 Series,
1987 Ford F-150 Lariat 302 ~ Decommissioned
2006 Honda Civic LX 1.6 ~ Totaled
2011 Acura TSX K24 Base ~ Daily Driver, Supercharged 10PSI, 310whp 241lb/ft
Reply With Quote
  #15  
Old 11-28-2014, 09:10 AM
Hlifted Ranger Hlifted Ranger is offline
Liking the Ford Ranger Forum
 
Join Date: Nov 2014
Posts: 23
Default Re: Bigger Tires & Speedometer

Quote:
Originally Posted by Vogenitz69 View Post
If the new tires are larger and spin more per rotation, your car is actually traveling 14% farther than what the odometer reads
Yea exactly, so its its saying I traveled LESS km per tank while burning MORE fuel. Therefore my MPG reading should be WORSE. But (according to my scangauge) my MPG is better (~25)

Now that part doesn't make sense to me, since if my truck thinks its travelling less on more fuel it should give me a lower (worse) MPG rating...
__________________
2011 Ford Ranger FX4 Sport:
|3'' Body Lift + Leveling Kit|Custom Built Off-Road Front Bumper|BF Goodrich All-Terrain Tires|Sony Stereo|10" Comp Sub|Non-existent Muffler|Knock-off Magnaflow Exhaust|
Reply With Quote
Reply

Tags
big tires, mpg, obdii reader, speedometer

Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
replaced with bigger sub, and bigger amp less sound? blakeK2 Audio / Video 56 01-09-2014 11:35 PM
new bigger amp but sub sounds worse? NFCTWC Audio / Video 24 12-19-2012 11:43 AM
can i run a bigger amp with this set up? rangerdanger6 Audio / Video 25 01-23-2012 08:45 AM
bigger tires? ranger_kid1 Wheels and Tires 6 01-19-2012 06:19 PM
bigger tires and a 3.0? bikerboy Wheels and Tires 7 11-22-2011 09:26 PM