Stagger tire size issue

[darknessxyz]

A buddy just put four new tires on his 02 WS6. The front are 275/40/17 and the rear is 295/45/17. After he put them on and drive for a couple miles, the ABS, TCS, E-brake light all on. Also when he step on the brake, it kick back.

I scan it and a code C0245 show up. I CANNOT DELETE IT. He said the light will turn off once he shut off the car. Then it'll turn back on after he start and drive for a couple miles.

I checked with my GM SI, this is what I found:
Circuit Description
The speed sensors used on the front of this vehicle are multiple pole and the rear uses a single pole magnetic pickup. This sensor produces an AC signal that the EBCM uses the frequency from to calculate the wheel speed.

Conditions for Setting the DTC

• The EBCM detects a deviation between the left and right rear wheel speeds of greater than 6 km/h (3.75 mph) at a vehicle speed of less than 100 km/h (62 mph) on vehicles equipped with TCS.
• The EBCM detects a deviation between the left and right front wheel speeds of greater than 10 km/h (6.25 mph) at a vehicle speed of less than 100 km/h (62 mph).
• The EBCM detects a deviation between the left and right rear wheel speeds of greater than 6 percent of the vehicle speed at greater than 100 km/h (62 mph) on vehicles equipped with TCS.
• The EBCM detects a deviation between the left and right front wheel speeds of greater than 4 km/h plus 6 percent of the vehicle speed at greater than 100 km/h (62 mph).

Is this bcuz the rear tire is bigger than the front so set off the code? How can I fix it?

[darknessxyz]

anyone?

[gman4dx266]

Seems as if its getting confused because the front and rear dont correlate between their readings. Being a Cxxxxx code you cant turn it off in the tune. Ive never had this happen to me, so you'll have to wait for someone else to chime in.

[12secSS]

It is a common issue with drag racers when they run slicks in the back with skinnies in the front. Like the setup in my picture. He will need to live with it. Why did he stagger the tire size using street tires? Why not go with the OE size? If he wanted wider tires in the back, he should have gone lower on the aspect ratio, not higher.

[darknessxyz]

The rear is not street tire, they're MT drag radial.

The problem is, this is his dialy driver and he wants to run those DR daily...

[Programmer]

Just fixed this for a client with a 'vette'...similar issue. Rescaled the ABS pulse to fix it.

[darknessxyz]

Just fixed this for a client with a 'vette'...similar issue. Rescaled the ABS pulse to fix it.

Do you mind give a little bit more detail...please.

[GRRRR8]

Having a similiar issue. Rears are 26.75 and fronts are 25.08 using the divide by 3.14 rollout method. How do you calibrate the ABS? By splitting the difference(25.92) the pedal is normal, but the light comes on over 50mph. The screwed up thing is the rear spec is 26.5(ET Street) and the frts 26(M&H 17 in runners) I can live with it, but I know there has to be a way.

[tording99z28]

With Fbodies I don't think there is a way to stop it except to get rid of the ABS system. If you get rid of the ABS system it also gets rid of the traction control system. I did this and I love having all that stuff gone. I can now run whatever tire combination I want and since I have a proportioning valve now I can tell the system how much I want the rear brakes to grab.

[Dragman]

I have had all kinda tires on my Vette no issues here!