Ok I got new set of rear tires, good year eagles. I was milking the kumho ecstas on the rear, both pretty much bald when I bought the car.

Before when tire pressure in one tire would get lower than the rest, the DSC and traction control lights would come on, with the DSC flashing. After driving a while this problem would seem to go away, or as soon as I fixed the pressure problem.

Now, however, after the new rear tires are installed these two lights stay on and never go off....is it because I have different front tires than on the rear? Can the car really tell this difference? They both air up to the same psi.

I know tires need to match from right to left but I didn't think it mattered from front to back...

 

I think the spec says if theres a speed difference bigger than 5% the system would throw a warning light.
being different manufactures even same size the circumference could be off more than 5% sometimes.

 

Well, a warning light I could understand, but this is turning off the dsc and traction control. Kinda unsafe. I'm just worried the tire shop screwed something up. Or if there's a way I can reset it.

Did a search and found nothing on the topic, but I'm pretty sure I'm not the only one with mismatched tires.

 

To reset the DSC, Start your car. Turn your wheels all the way to the right, then turn them all the way to the left. Shut off the car and restart. The DSC light should be reset.

 

I think you only have to restart car to reset traction control.

I tracked my car with Kumho Ecsta SPT's on the back nearly worn out, and new Hankook Evo Ventus V12's on the front new, and my 8 bucked me off (spun 360 deg which I wouldn't have done with traction off) on a slow corner.

The traction-stability control system works very well, but it really needs all 4 tires to be exactly alike; they can be new or worn on any position, but it can tell the difference between grip levels even if the tires are same rolling diameter.

 

Yeah, I just went through this, although I have the same tires (Goodyear Eagle F1 All Season) all around. Replaced just the rears, and DSC/Traction Control kept kicking in, especially in hard right turns. Had them rotated, so that new tires were on the front. That seemed to stop the DSC/Traction Control problem, but the care still "felt" less stable to me. Broke down and bought the other 2 tires, and now it feels solid again. Like REDRX3RX8 said, it seems very sensitive to differences in tire diameter and/or traction. But even when the Traction control was not kicking in, I could feel the difference.

 

Well, the problem is that the DSC and traction control are now automatically off...


Cash is tight for me so buying two more new tires any time real soon isn't an option.


I'll try resetting the DSC, which I don't understand why it's acting up due to the fact that DSC is all about the rear, which do match.

 

DSC is not all about rear. DSC allows braking on individual wheel to control understeer and oversteer. it monitors all four wheels. so if you have front rear tires spinning at different speed, it would think the wheels that are spinning faster are slipping, but of course its set that it turns off if theres a constant slippage when going straight, which is pretty much your case.

 

Oh ok, thanks for the info.

I thought traction control was what did that. So it leaves the question, what does traction control do?

 

traction control limits the slippage of the rear tires. it works by limiting power from the engine when rear tires are spinning faster then the front tires. also when rear tires are on different surfaces that have different friction, it applies brake to the one thats spinning faster to send the power to the one has the higher grip (if you know how a diff works).

heres a vid that explains ABS, traction control, and ESP (DSC on RX8) pretty clearly.
http://www.youtube.com/watch?v=wR1SSxpKitE