jclaus98

So, here's the deal, I discovered my precious C63 needed new shoes at an incredibly inopportune moment financially and this being the first set of tires I've put on this beast, I went with a set of random 265/40R18's from the local tire guy I trust. He will swap sets of tires out if they don't feel right or they vibrate, etc. So, these no name brand tires work fine going back and forth to work (I never need to touch a freeway to get to work and back) but the first day I get it out on the freeway, both getting on the freeway and getting off, at roughly 40-50 mph on the on/off ramps, the traction control freaks out and is constantly trying to brake the rear wheels. Has this happened to anyone else? I'm obviously considering a different set of tires, but curious if anyone else has experienced this or not? Go ahead and scold me for not putting the right tires on it, I knew better but figured some tread was better than none at the time. I am definitely an idiot but plan on fixing my mistake. At any rate, this car is never tracked, just the occasional spirited discreet driving to work and back. Thanks gents.

m a x i m u s

Could be bc the the rear wheel overall diameter changed due to the 40 aspect 265's. I've seen ABS, etc. becoming inoperable in these cases, but actually never heard of the traction control kicking in with the rear brakes trying apply themselves. If you go back to 35's, I'll bet your problems will be solved.

zcct04

This is a first, I think! Never heard of traction control freaking out.

Can you describe exactly what you are seeing and feeling when this happens?

Jasonoff

I think absolute max for the ESP module is 5% which you are slightly over.

CarHopper

Yup, you've got the wrong tire size.

jclaus98

It's pretty wild actually, it will brake the rear wheels independently at random times, even though there is no slipping of any kind. And it's only on the on/off ramps where I'm moving at a pretty decent speed with a fairly decent banking. Very weird.

jclaus98

Is there a way to reset the ESP ECM to accept the larger tire or is that a pre-programmed value that can't ever be changed? I could swear I'd heard of people here who were running 40 aspect ratio tires and didn't have any issues of these kinds, but I could be wrong...

CarHopper

Depends on the tire, but you have an off brand which could also play into it. And the problem you have is minor. Like, your car is telling you it is JUST off which is why you only experience it from that 40-50 interval.

As for programming, no idea. I bet there is, but I bet that costs way more than a proper set of tires.

When you can, just get a set of 265/35/18 MPSS tires and your problems will be solved with one of the best street tires out there.

QWKSNKE

yep, 35 series is what you need on the back. 40 series is reserved for the front. (of course this all depends on your tire width as it plays a factor in 35/40 series of the sidewall)

agentMurdoc

How much did you pay for said cheap tires? I ask cause there are some good tires in the middle spectrum of cost.

bhamg

My guess is that the cheap tires have resulted in slippage that you may not even notice normally, but which activates the braking component of traction control. And, it may be exacerbated by an unexpected rotational difference caused by the off-spec tire measurements. Just a theory but it strikes me as very possible.

Jasonoff

No. The OD of your tire is 5.2% larger than OEM. It's outside the range of what the ESP module can handle.

If someone else had a 40 it was likely a 255 or narrower.

Get the right tire size and you'll be sorted.

/thread

jclaus98

Thanks gents. Greatly appreciated.

jclaus98

Ok gentlemen, the saga continues. Went down to Schwab and got myself some Nitto 265/35R18's for the rear, my wallet is still screaming. However, the traction control is still on the fritz, as if to give me the big ol' middle finger. I'm thinking perhaps a wheel sensor is out whack or something? Any ideas what could be causing these symptoms? To recap: fine going straight, under acceleration, tight turns, wide turns, etc., however, every time I hit an on ramp or an off ramp to/from a freeway, the traction control is stabbing at the brakes in an attempt to control a phantom slip. Please help. Thanks.

Jasonoff

Possibly the yaw sensor or the ESP module is faulty. Maybe bad wheel bearing.

bhamg

Correct me if I'm wrong but the theory behind most if not all of these electronic stability control systems is that through the combined input of the sensors (primarily the steering wheel) involved, the system determines whether your car is actually going in the direction that you intended. If not it will selectively brake the wheel(s) that will effectively correct that situation. I would look to the steering also.

Jasonoff

Get the steering angle sensor reset. I think 5 lock to lock cycles will do it as well.

jclaus98

Excellent input gentlemen, thank you. I'm wondering if perhaps one of the tone rings is out of alignment or possible that the air gap between the tone ring and the sensor has been disturbed? This has only presented itself since the first set of tires were installed, so I'm going to assume that something changed during that first install and that's where my problem is. Does anyone know the tone ring to wheel sensor clearance number off the top of their head? I'll try resetting the steering sensor as well. Thanks again to all.

Jasonoff

It gets dirty as f__k in the rear.

The ring is coated in plastic so it's smooth, but it gets loaded with brake dust. Yank the sensor from the knuckle and spray some cleaner in the hole while rotating the wheel to clean it out.

That worked when I first started getting the ESP warning.

jclaus98

Good suggestion Jason, I'll try that tonight.

hachiroku

after i put on my Vossen 20 inchers my ESP got real real sensitive. any bump in the road causes my throttle to shut. i thought my car was broken as i've never felt this before in normal driving.

Mag1c Carp3t

Is this % calculated between front and rear wheel diameters or from oem spec to current spec diameters of the single wheel?

Jasonoff

Delta between sensors. But that wasn't the problem here.

zcct04

Delta between front and rear TIRE diameters.