New tires and Active traction problems.
Thread Starter
2nd Gear
Joined: Sep 2004
Posts: 2
Likes: 0
New tires and Active traction problems.
Just replaced the Goodyear EMT's with Pirelli P Zeros on my 2001 coupe. The front are the original size (245/45-17) but I ended up putting 285/30-18 on the rear (I did not want to go with the smaller diameter tire but they were a good deal).
Took it for a test drive and when I get to 45 mph the active traction handling comes on and will not let me accelerate and further. I am having to drive with the active traction off.
I think the problem is with the new tire size. The rear wheels are making more turns at a given speed since their diameter is smaller then OE. Can I reset the computer so it won't think I am loosing traction?
Thank you for any thoughts on the matter.
Paul
Took it for a test drive and when I get to 45 mph the active traction handling comes on and will not let me accelerate and further. I am having to drive with the active traction off.
I think the problem is with the new tire size. The rear wheels are making more turns at a given speed since their diameter is smaller then OE. Can I reset the computer so it won't think I am loosing traction?
Thank you for any thoughts on the matter.
Paul
Last edited by strakap; Jul 23, 2005 at 08:39 AM.
Racer
Joined: Apr 2004
Posts: 391
Likes: 7
From: Garland Texas
wrong side wall hight you have to reprogram the your computer for the side wall hight. I did it my self, went back to a taller tire on the back. The computer has to see a one inch from front to back tires.
Good luck
Good luck
Le Mans Master
Joined: Sep 2004
Posts: 7,027
Likes: 6
From: Shiloh Ohio
Originally Posted by strakap
Just replaced the Goodyear EMT's with Pirelli P Zeros on my 2001 coupe. The front are the original size (245/45-17) but I ended up putting 285/30-18 on the rear (I did not want to go with the smaller diameter tire but they were a good deal).
Took it for a test drive and when I get to 45 mph the active traction handling comes on and will not let me accelerate and further. I am having to drive with the active traction off.
I think the problem is with the new tire size. The rear wheels are making more turns at a given speed since their diameter is smaller then OE. Can I reset the computer so it won't think I am loosing traction?
Thank you for any thoughts on the matter.
Paul
Took it for a test drive and when I get to 45 mph the active traction handling comes on and will not let me accelerate and further. I am having to drive with the active traction off.
I think the problem is with the new tire size. The rear wheels are making more turns at a given speed since their diameter is smaller then OE. Can I reset the computer so it won't think I am loosing traction?
Thank you for any thoughts on the matter.
Paul
http://discounttire.com/dtcs/infoTireMath.dos
Tech Contributor
Joined: Oct 1999
Posts: 41,058
Likes: 9,820
From: Charlotte, NC (formerly Endicott, NY)
You can't reprogram the ABS/TC/AH computer. It is separate from the PCM. You are getting both brake activation on the rear brakes and reduced throttle. If you coast down a hill in nuetral fast enough the rear brakes will activate to keep the wheels from spinning. You need to get larger rear diameter tires or swap the fronts and rears. Run the 18s on the front and the 17s on the rear.
Bill
Bill
Le Mans Master
Joined: Sep 2004
Posts: 7,027
Likes: 6
From: Shiloh Ohio
You could sell either the front or rear tires here on the forum and replace with an appropriate size. You will lose a little money but you really can not run like that. Unless of course you switch front and rear like the one member suggested. 
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Race Director
Joined: Oct 2002
Posts: 16,477
Likes: 26
From: Gone
CI 6-7-8-9-10 Veteran
St. Jude Donor '03
Originally Posted by bbvett
I remember the Predator tuner enabled tire size ajustment. Expensive fix.
Either switch to proper height tires, or learn to live w/o traction control and active handling...those are the only two options.
Le Mans Master
Joined: Sep 2004
Posts: 7,027
Likes: 6
From: Shiloh Ohio
Originally Posted by Y2Kvert4me
That only is for speedometer calibration. It does not affect the TC module.
Either switch to proper height tires, or learn to live w/o traction control and active handling...those are the only two options.
Either switch to proper height tires, or learn to live w/o traction control and active handling...those are the only two options.
That is your only option.
Instructor
Joined: Jul 2000
Posts: 221
Likes: 30
From: columbia mo.
I Am Having The Same Problem The Rear Tires Are One Tenth Smaller In Diameter. Comes Up Traction Control Active Then Nothing And Turn Control Off Just Fine. When Shut Car Off It Is Fine Untill Get To Highway Speed. Havent Looked To See If It Starts At 40 Or Just Above.
Team Owner
Joined: Mar 1999
Posts: 28,753
Likes: 9
From: San Jose/Bear Valley CA
CA Events Coordinator
Maybe it would be best if a blanket statement was made... the front tires are supposed to be 1" smaller outside diameter than the rears..... Now some C5's can run with them close to the same size... and one wont know that until they try it. NONE of them can run with the rear tire smaller (outside diameter) than the front.
So go out and buy the correct tires for the car this time. If you have any questions of what tire combinations will work, please feel free to ask.
VR
So go out and buy the correct tires for the car this time. If you have any questions of what tire combinations will work, please feel free to ask.
VR
Last edited by vetterdstr; Jul 30, 2005 at 07:41 AM.