18" Wheels all around - Got a problem
Safety Car
Joined: May 2003
Posts: 3,814
Likes: 105
From: Dearborn Heights Michigan
Re: 18" Wheels all around - Got a problem (Ragtop_Rob)
I run 265/35/18 frt & 295/35/18 rr with no problems on C5 Coupe (not ZO6.) I have read if the front to rear ratio is 96% or greater that no problems will happen. Your prob is a puzzle.
Fred K.
Fred K.
Melting Slicks
Joined: Mar 2001
Posts: 2,369
Likes: 51
From: New Milford CT
Re: 18" Wheels all around - Got a problem (pinot)
Pinot, I have the Nitto 305/35/18's on the rear at 26.3" tall. You can get them in the Drag radials (555R) like I have, or the same tire in a Road race variation (555RII). Identical in looks, size and tread compound and tread pattern, but with a stiffer sidewall.
By the way the "drag radials" are very hard to tell from ordinary Vette tires in there cornering ability. I can't see any difference at all really.
By the way the "drag radials" are very hard to tell from ordinary Vette tires in there cornering ability. I can't see any difference at all really.
Tech Contributor
Joined: Oct 1999
Posts: 41,036
Likes: 9,798
From: Charlotte, NC (formerly Endicott, NY)
Re: 18" Wheels all around - Got a problem (pinot)
I am surprised you are getting up to 60. When I did a test with larger tires on the front and coasted down hill at 10 the EBTCM applied the rear brakes to control rear wheel slip. The EBTCM sends a signal to the PCM requesting desired torque there is no signal path the other way. I doubt you can change the programming without having a special computer designed to talk to the EBTCM. The AH/TC/ABS systems are tuned for a compromise of different road surfaces, wet surfaces and ice. Unless you are an engineer knowledgeable in that area you really shouldn't be messing with it.
Bill
Bill
Thread Starter
Instructor
Joined: Jun 2003
Posts: 147
Likes: 0
From: Fort Myers FL
Re: 18" Wheels all around - Got a problem (Bill Dearborn)
OK, I have resigned myself to replacing the tires. If all of us a group can't lick this one, I have to move on. Problem is that I will have to replace all 4 to solve the problem as neither the axle can be bought in the correct size and stay in the F1 SC tire. I will prolly wind up getting 4 new F1 DS so I can aslo solve the hydroplabe issue while I am at it. Looks like I am manually turning off TC until these 4 shoes wear out. Think I will be turning TC back on in the rain.
Bill - Yeah, 50-60 MPH seems to be the avg speed where the message kicks in for those of us with this issue. I have driven my 2001 and several other 2003 on track and never seen rear brakes applied by puters. The system goes on then makes it presence known by dialing out timing, no brakes to my knowledge. Perhaps older C5 have what you speak of, but this does not make sense as a driver could still press the go pedal and reak havoc with the whole system. I am not sure there is any direct communication between the TC and PCM. Looks like the TC acts independantly of PCM is this case anyway. Being that the PCM is supposed to be the hub for all info, your one way theory does not make sense, but I really don't know. Time for a GM insider to chime in here.
Pinot
Bill - Yeah, 50-60 MPH seems to be the avg speed where the message kicks in for those of us with this issue. I have driven my 2001 and several other 2003 on track and never seen rear brakes applied by puters. The system goes on then makes it presence known by dialing out timing, no brakes to my knowledge. Perhaps older C5 have what you speak of, but this does not make sense as a driver could still press the go pedal and reak havoc with the whole system. I am not sure there is any direct communication between the TC and PCM. Looks like the TC acts independantly of PCM is this case anyway. Being that the PCM is supposed to be the hub for all info, your one way theory does not make sense, but I really don't know. Time for a GM insider to chime in here.
Pinot
