Guys,

Just had tires installed minutes ago and as I exited the shop I felt the ABS actuator kick in twice. Then the lights. Did they come on because the tires are mismatched?

Front, new: 235/40/18
Rear: old: 245/45/18

The answer might be obvious but I just want to make sure. If so, this will be an expensive lesson. Grrrrr

Update: I know the lights can come on when the brake pads are low and thus forces more fluid in from the reservoir. Pads are near the end of life and fluid is just below max.

I am wondering if its actually the pads or the tires since the light came on as I was leaving the tire shop. Could it be coincidence?

Thanks

 

YEP! The car does not like old tires mixed. MY GF coupe did the same thing, her tires needed to be replaced and the front was worn out. So the slip light and brake like keeps coming on and off.

So you need to replace the back to correct it.

 

Its the difference in sidewall height..supposed to be 45 all the way around...So wheel sensors are reading them at different speeds causing the abs to kick in when braking....And at hwy speeds all the lights come on..Why did you not go with the recommended 225/45/18 for front?

 

Thanks for confirming what I suspected. Great explanation. I had the stock size and should have replaced with the same. I went with the 235/40/18 so that I would have more clearance if I lower but the difference is negligible. Dumb move on my part.

I doubt the tire shop will do anything for me. Other than selling these at a loss more than likely and getting the correct size, changing the rears to a 40 series (255/40/18?) might be my best bet.

 

Yup, tire diameters are off. Nothing wider than the 245's will really fit right on the rear. I'd go oe sizes to keep all happy.