Does a slightly shorter tire screw up the computer?
Thread Starter
|
Senior Member
Joined: Apr 2000
Posts: 1,173
Likes: 0
From: Allen, TX, USA
Does a slightly shorter tire screw up the computer?
Hey guys,
I'm still considering some wider rear tires for my Lightning. I'm wondering if I did nothing but go from the stock 28.5" tall tire to a 27.5" tall if that would screw up the computer, especially the shift points.
For you guys who run 26" ET Streets/ET Drags, or a shorter-than-stock Drag Radial...what happens at the track? Does your truck still shift at the same rpms as it does on the street? Obviously, you will turn more rpm for a given MPH, but I'm concerned with shift points. I don't want the computer to get all freaked out if I effectively increase the rear gear ratio a bit by running a 1" shorter rear tire.
------------------
Wes Tarbox
90 LX 5.0 (10.69 @ 134.7)--597rwhp/590rwtq
96 Cobra (12.34 @ 115.8)--392rwhp/433rwtq
99 Lightning (13.20 @ 103.8)--364rwhp/447rwtq
00 Expedition XLT 5.4
http://hometown.aol.com/wa2fst/home.htm
I'm still considering some wider rear tires for my Lightning. I'm wondering if I did nothing but go from the stock 28.5" tall tire to a 27.5" tall if that would screw up the computer, especially the shift points.
For you guys who run 26" ET Streets/ET Drags, or a shorter-than-stock Drag Radial...what happens at the track? Does your truck still shift at the same rpms as it does on the street? Obviously, you will turn more rpm for a given MPH, but I'm concerned with shift points. I don't want the computer to get all freaked out if I effectively increase the rear gear ratio a bit by running a 1" shorter rear tire.
------------------
Wes Tarbox
90 LX 5.0 (10.69 @ 134.7)--597rwhp/590rwtq
96 Cobra (12.34 @ 115.8)--392rwhp/433rwtq
99 Lightning (13.20 @ 103.8)--364rwhp/447rwtq
00 Expedition XLT 5.4
http://hometown.aol.com/wa2fst/home.htm
Senior Member
Joined: Mar 2000
Posts: 6,798
Likes: 0
From: TEXAS
Wes I posted a Tire Calculator on my site about a week ago - Check it out- It will tell you the Speedo error to expect.
Doug
------------------
Picked up Silver 2000 Lightning 2/28/00!!
1st run 13.9 sec 1/4 !! Best Run 13.25
drbdkb@hotmail.com
www.SVTLightnings.com
2000 Lightning, FMS 3.73 gears ( Expensive ), PSP 4 Way Chip, PSP Intake, Valentine 1, Snuglid, Bedrug, Lighted Ford Logos, Superchip R9, and 3m Panther Black nickel tint, Clear corners., Boston Acoustics 5x7s and Components, Alpine v12 5 channel Amp and JL Sub, Chrome SVT Rims and G Force R1a Autocross Tires, .
Doug
------------------
Picked up Silver 2000 Lightning 2/28/00!!
1st run 13.9 sec 1/4 !! Best Run 13.25
drbdkb@hotmail.com
www.SVTLightnings.com
2000 Lightning, FMS 3.73 gears ( Expensive ), PSP 4 Way Chip, PSP Intake, Valentine 1, Snuglid, Bedrug, Lighted Ford Logos, Superchip R9, and 3m Panther Black nickel tint, Clear corners., Boston Acoustics 5x7s and Components, Alpine v12 5 channel Amp and JL Sub, Chrome SVT Rims and G Force R1a Autocross Tires, .
Senior Member
Joined: Jun 2000
Posts: 857
Likes: 0
From: Downriver, Michigan
Your computer measures "revolutions per mile" If you go to a shorter tire, guess what, more revolutions that will add up to more miles that actually aren't accumulating. You would need to accomodate the tire change to correct your speedo.
Senior Member
Joined: Sep 2000
Posts: 355
Likes: 0
From: Lewisville, TX USA
Well, I am going to say it porbably does mess with the ABS, anyway. Ever since Ford replaced two of my tires a week or so ago because of the aligment problem, the ABS has engaged on dry pavement with anything over say 40% brake pressure. They tried everything to fix it, and in the end, the solution was two more new tires, so they all had approximate diameter. Apparently, the 2001MY F1s have deeper tread than did 2000, so the diameter difference between my 10000 mile 2k model tires and the brand new 01MY ones they put on was too great, and fooled the ABS into engaging incorrectly.
So in the end, the alignment problem cost Ford 4 brand new F1s, plus parts and labor of fixing the problem in the first place.
So in the end, the alignment problem cost Ford 4 brand new F1s, plus parts and labor of fixing the problem in the first place.
Thread Starter
|
Senior Member
Joined: Apr 2000
Posts: 1,173
Likes: 0
From: Allen, TX, USA
Thanks all.
I understand it will add a few more miles if the computer is not recalibrated. I was more concerned with the shifting b/c on some late model Mustangs with auto trannies, the Vehicle Speed Sensor has input to when the trans shifts. So, if the thing _thinks_ its going faster than it is, it will short-shift.
Still...it all sounds like it might not be worth it.
------------------
Wes Tarbox
90 LX 5.0 (10.69 @ 134.7)--597rwhp/590rwtq
96 Cobra (12.34 @ 115.8)--392rwhp/433rwtq
99 Lightning (13.20 @ 103.8)--364rwhp/447rwtq
00 Expedition XLT 5.4
http://hometown.aol.com/wa2fst/home.htm
I understand it will add a few more miles if the computer is not recalibrated. I was more concerned with the shifting b/c on some late model Mustangs with auto trannies, the Vehicle Speed Sensor has input to when the trans shifts. So, if the thing _thinks_ its going faster than it is, it will short-shift.
Still...it all sounds like it might not be worth it.
------------------
Wes Tarbox
90 LX 5.0 (10.69 @ 134.7)--597rwhp/590rwtq
96 Cobra (12.34 @ 115.8)--392rwhp/433rwtq
99 Lightning (13.20 @ 103.8)--364rwhp/447rwtq
00 Expedition XLT 5.4
http://hometown.aol.com/wa2fst/home.htm