Problem w/ dash lights after tire/rim change

**Y2K_CAMARO** · 11-17-2008, 01:45 AM

I have had no problems with my car at all. It is a 2000 Camaro Z28 M6 with 66,500 miles. Maybe its just a coincidence that it happened after a tire/rim change, but I'm giving you all info. I had 18" rims with 245/40's on the front, and 275/35's on the rear. I just changed them out for 17" rims with 245/40's on the front and 275/50's on the rear. Now, at start up, everything is fine, but once I get at a steady speed of over like 35-40mph, the following lights come on, "ABS INOP", "ASR OFF" (but traction control still works, and cant be turned on or off while "ASR" light says its off), and the "BRAKE" as in the E-brake is up. I can turn off the car, then back on and lights are not on, but then I reach that certain speed again and they come back on. I have tried disconnecting the battery, but that didn't do anything. I haven't had codes read yet, I know its throwing a code because I have no cats, but I haven't checked it to see if it's throwing anything else. Please, any idea's?

**SSTODD** · 11-17-2008, 07:34 AM

Sounds like you have a difference in diameter from front to rear and your sensors don't like that with abs and traction control. factory SS is 275/40/17 all around 25.7" I think. 245/50/16 on a Z28 but same height. Your numbers posted don't seem correct?

**SteveC** · 11-17-2008, 07:40 AM

Originally Posted by SSTODD

Sounds like you have a difference in diameter from front to rear and your sensors don't like that with abs and traction control. factory SS is 275/40/17 all around 25.7" I think. 245/50/16 on a Z28 but same height. Your numbers posted don't seem correct?

BINGO!!!, This is what happens when you have a difference in the diameters of the tires on the vehicle, I am running 285X35XZR18 all the way around, and have no issues with the ABS (I do not have traction control).

When there is a difference in the rolling mass the ABS system reads it as the tires are slipping.

SteveC

**Y2K_CAMARO** · 11-17-2008, 07:59 AM

Originally Posted by SSTODD

Sounds like you have a difference in diameter from front to rear and your sensors don't like that with abs and traction control. factory SS is 275/40/17 all around 25.7" I think. 245/50/16 on a Z28 but same height. Your numbers posted don't seem correct?

Originally Posted by SteveC

BINGO!!!, This is what happens when you have a difference in the diameters of the tires on the vehicle, I am running 285X35XZR18 all the way around, and have no issues with the ABS (I do not have traction control).

When there is a difference in the rolling mass the ABS system reads it as the tires are slipping.

SteveC

Well what about the difference in the tires when I had the 18's on the car? I had no problems then

**SSTODD** · 11-17-2008, 08:05 AM

you had 40's on the front and 35's on the rear so the height was probably close. now you are too tall with 50's in back. you need to look at a manufacturer tire chart for your sizes and see the diameters of each. the first number is the width (275) but the 35,40,50 affects the height.

**Y2K_CAMARO** · 11-17-2008, 10:48 AM

Ok, but I can just get it calibrated for the bigger tires right?

**SteveC** · 11-17-2008, 03:43 PM

Originally Posted by Y2K_CAMARO

Ok, but I can just get it calibrated for the bigger tires right?

You need to have the same tire OD all the way around.

SteveC

**SSTODD** · 11-18-2008, 02:12 AM

I've never heard of a 275/50/17 for our cars? Check your numbers again, but if you go narrow in front the aspect ratio needs to be bigger (50) and the wider rear needs to be (35, or 40) so the OD is about the same. See tirerack.com and look at specs of tires and the diameters.

**Y2K_CAMARO** · 11-18-2008, 02:22 AM

Originally Posted by SSTODD

I've never heard of a 275/50/17 for our cars? Check your numbers again, but if you go narrow in front the aspect ratio needs to be bigger (50) and the wider rear needs to be (35, or 40) so the OD is about the same. See tirerack.com and look at specs of tires and the diameters.

That number is correct. A 275/50/17 M&H drag radial

**SSTODD** · 11-18-2008, 02:42 AM

WOW, that is a tall tire, you may need a (60 or 70) series up front to match that diameter in the rear.

**Y2K_CAMARO** · 11-18-2008, 02:44 AM

Yea, or I could just put the other rims and tires on there for when I drive on the street

**01 SS Vert** · 05-29-2009, 02:23 PM

I have this same issue:

275/40/17s Front
315/35/17s Rear

I just did a thread on my problem. Anything I can do without changing tires? It's even happened with 275/40s on all 4 corners, so I'm stumped.

**Cutlass** · 05-29-2009, 05:50 PM

Y2K CAMARO,
245/40R18 is 25.7" tall
275/35R18 is 25.6" tall
Close enough
245/40R17 is 24.7" tall
275/50R17 is 27.8" tall
NOT close enough, there's your problem