Tire size change
Thread Starter
|
New User
Joined: Aug 2006
Posts: 1
Likes: 0
Tire size change
I Have A 2004 F350 4x4 6.0 I Have Change My Tire Size From 265/75/r16
To 305/70/r16 The 265 Are 31.7 In And The 305 Are 33.0 In Tall The
Transmission Is Not Shifting Like It Did Before Can I Have It Program
To Shift Like It Used To I Have Lost Fuel Mileage I Do Not Know If It
Has Any Thing To Do With The Size Of The Tires Or The Transmission
Shifting Thanks For Any Help
To 305/70/r16 The 265 Are 31.7 In And The 305 Are 33.0 In Tall The
Transmission Is Not Shifting Like It Did Before Can I Have It Program
To Shift Like It Used To I Have Lost Fuel Mileage I Do Not Know If It
Has Any Thing To Do With The Size Of The Tires Or The Transmission
Shifting Thanks For Any Help
Tuned
Joined: Nov 2005
Posts: 267
Likes: 5
When you talk about not shifting the way it was, do you mean under all types of driving conditions? I'm guessing, and I stress "guess" that under heavy acceleration the taller tire would cause the tranny to wait until a higher rpm to shift to the engine having to work a little harder.
I hope someone who really knows can answer. I'm waiting on a set of 305/65/18 to replace my stock 275/70/18 due to the fact that the only available tire in NM in my size is the Continental that came on the truck and I would not take these if they were given to me so there's absolutely no way I'll pay for them. Due to Goodyears strike I cant get the Wrangler so I was left to improvise. Even at that I've had a very difficult time trying to get the ones I've ordered. I can't believe something as mundane as buying tires would be so difficult. Its stupid.
I hope someone who really knows can answer. I'm waiting on a set of 305/65/18 to replace my stock 275/70/18 due to the fact that the only available tire in NM in my size is the Continental that came on the truck and I would not take these if they were given to me so there's absolutely no way I'll pay for them. Due to Goodyears strike I cant get the Wrangler so I was left to improvise. Even at that I've had a very difficult time trying to get the ones I've ordered. I can't believe something as mundane as buying tires would be so difficult. Its stupid.
Postmaster
Joined: Aug 2006
Posts: 2,829
Likes: 3
Changing the tire size on a MY04 will not effect the transmission shifting in anyway. The vehicle does not use wheel speed sensors for transmission shift points.
I just changed mine from stock 275/65R18's (32.1" tall) to 35X12.5R18. Nothing has changed in the performance of the transmission, braking/ABS, etc.
Now when it comes to fuel economy and bigger tires , you will lose some in the city, but should be better on the highway. I do approximately 60% highway and 40% city and have actually gained about 1.2 mpg overall.
I just changed mine from stock 275/65R18's (32.1" tall) to 35X12.5R18. Nothing has changed in the performance of the transmission, braking/ABS, etc.
Now when it comes to fuel economy and bigger tires , you will lose some in the city, but should be better on the highway. I do approximately 60% highway and 40% city and have actually gained about 1.2 mpg overall.
Last edited by PowerStrokeHD; Dec 31, 2006 at 01:01 AM.
Former Vendor
Joined: Mar 2004
Posts: 4,362
Likes: 3
From: Hendersonville, NC
Originally Posted by PowerStrokeHD
Changing the tire size on a MY04 will not effect the transmission shifting in anyway. The vehicle does not use wheel speed sensors for transmission shift points.
The SD reads its vehicle speed from the rear ring gear, so tire size does affect it, because you have changed the N/V value of the vehicle. The N/V ratio in the computer is however self adaptive, and will correct its shifting over time down to a 27 inch tire, up to a 34.6 inch tire.
The speedometer is not self adaptive, and will need to be recalibrated by the dealer for true accuracy.
Postmaster
Joined: Aug 2006
Posts: 2,829
Likes: 3
Originally Posted by PSD 60L Fx4
Not entirely true.
The SD reads its vehicle speed from the rear ring gear, so tire size does affect it, because you have changed the N/V value of the vehicle. The N/V ratio in the computer is however self adaptive, and will correct its shifting over time down to a 27 inch tire, up to a 34.6 inch tire.
The speedometer is not self adaptive, and will need to be recalibrated by the dealer for true accuracy.
The SD reads its vehicle speed from the rear ring gear, so tire size does affect it, because you have changed the N/V value of the vehicle. The N/V ratio in the computer is however self adaptive, and will correct its shifting over time down to a 27 inch tire, up to a 34.6 inch tire.
The speedometer is not self adaptive, and will need to be recalibrated by the dealer for true accuracy.
I was just going buy another article I read on the subject, as well as the person who is going to adjust the RPM's for proper speedometer calibration. I am very confident with his knowledge on Ford electroinics, as it is his occupation. He works with Ford and International engineers, among others. Working on both production and prototype vehicles.
The shift scheduling on a '04 is determined by the...
OSS - Output Shaft Sensor
TSS/ISS - Turbine Shaft Speed/Intermediate Shaft Speed
These sensors combined control how the transmission shifts. I guess you would call it adaptive, yet mine performed the same when I took it in with stock tires as it did when I took it home. No adaptive time needed, it just shifted as it should.
Last edited by PowerStrokeHD; Dec 31, 2006 at 04:29 AM.
Posting Guru
Joined: Jul 2006
Posts: 1,191
Likes: 0
From: New York
What gears do you have on your truck? when you go with larger diameter tires, you do change the final gear ratio which is why you feel the difference. Also the fuel economy loss.
Trending Topics
Elder User
Joined: Sep 2006
Posts: 622
Likes: 0
From: Lincoln, NE
Assuming the 04's are like the older ones, changing my speedo was simply a matter of plugging into the OBDII and entering a new tire size. Unfortunately for me, there's a limited selection available to select from. We went with the closest diameter and then timed it. Only a couple seconds off at 60mph. Good enough.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Postmaster
Joined: Aug 2006
Posts: 2,829
Likes: 3
Originally Posted by TwelveAlpha
Assuming the 04's are like the older ones, changing my speedo was simply a matter of plugging into the OBDII and entering a new tire size. Unfortunately for me, there's a limited selection available to select from. We went with the closest diameter and then timed it. Only a couple seconds off at 60mph. Good enough.
Senior User
Joined: Sep 2003
Posts: 411
Likes: 2
From: KS
Originally Posted by PSD 60L Fx4
Not entirely true.
The SD reads its vehicle speed from the rear ring gear, so tire size does affect it, because you have changed the N/V value of the vehicle. The N/V ratio in the computer is however self adaptive, and will correct its shifting over time down to a 27 inch tire, up to a 34.6 inch tire.
The speedometer is not self adaptive, and will need to be recalibrated by the dealer for true accuracy.
The SD reads its vehicle speed from the rear ring gear, so tire size does affect it, because you have changed the N/V value of the vehicle. The N/V ratio in the computer is however self adaptive, and will correct its shifting over time down to a 27 inch tire, up to a 34.6 inch tire.
The speedometer is not self adaptive, and will need to be recalibrated by the dealer for true accuracy.
Elder User
Joined: Aug 2006
Posts: 501
Likes: 0
From: Eastern Ohio
Question? If my 05 came stock with 17'' wheels and the newer ones come with 20'' wheels and both have the same overall gear ratio of 3.73 are the newer ones actually geared lower to begin with to get this final ratio? I would assume the tires are not the same height unless they were of a lower profile?
Postmaster
Joined: Aug 2006
Posts: 2,829
Likes: 3
Originally Posted by 50calmike
Question? If my 05 came stock with 17'' wheels and the newer ones come with 20'' wheels and both have the same overall gear ratio of 3.73 are the newer ones actually geared lower to begin with to get this final ratio? I would assume the tires are not the same height unless they were of a lower profile?
Senior User
Joined: May 2003
Posts: 210
Likes: 0
From: Goodrich IL
All SRW PowerStrokes come with 3.73 no if's n's or but's!
DRW PowerStrokes have a few options.
All gas SRW or DRW have options.
And yes the 20in wheels have a taller tire which in turn throw the 3.73 ratio out!
Stock gas now comes with 4.10 along with the 17in rims.
Now what burns my arss is a 20in rim on a gasser with 4.10 gears!
Seeing how the 20in rim comes with a 34in tire they should come stock with 4.30 gears
I guess the same goes for a PowerStroke taller tire needs a taller gear.
Taller tire will effect trans shifts, as in lugging the engine = more fuel, kinda like towing a lite load.
Anyone who decides to run taller tires needs to understand the effects!
Taller tire needs a taller gear # towing heavy also needs a taller gear #
DRW PowerStrokes have a few options.
All gas SRW or DRW have options.
And yes the 20in wheels have a taller tire which in turn throw the 3.73 ratio out!
Stock gas now comes with 4.10 along with the 17in rims.
Now what burns my arss is a 20in rim on a gasser with 4.10 gears!
Seeing how the 20in rim comes with a 34in tire they should come stock with 4.30 gears
I guess the same goes for a PowerStroke taller tire needs a taller gear.
Taller tire will effect trans shifts, as in lugging the engine = more fuel, kinda like towing a lite load.
Anyone who decides to run taller tires needs to understand the effects!
Taller tire needs a taller gear # towing heavy also needs a taller gear #
FTE Leadership Emeritus
Joined: Sep 2000
Posts: 23,174
Likes: 1,678
From: Stephensville WI
By changing from a 31.7 inch tire to a 33 inch tire, you changed your effective differential ratio from 3.73 to 3.58. You would have to install something close to a 3.88 ratio to keep it like it was stock. Not a huge change but one that will be noticed.
It will change the way the trasmisssion feels and shifts. You might try the disconnecting the battery to clear the programming and then the "Torqushift Shift Relearning Strategy" from this web site:
http://home.austin.rr.com/sbv1/Proce...ngStrategy.htm
It will change the way the trasmisssion feels and shifts. You might try the disconnecting the battery to clear the programming and then the "Torqushift Shift Relearning Strategy" from this web site:
http://home.austin.rr.com/sbv1/Proce...ngStrategy.htm