AngelSpeedFreak

Hey guys,

I recently pickup up some CCW C14's and I just cannot figure out what the problem is.

They mount up perfect, the front does require a 5mm spacer to clear the front brakes.

Back wheels are 18x13 with MT 345/35/18's
Front wheels are 18x10 with Hankook v12 285/35/18's

Wheels all seem to spin freely when in the air, and the car drives fine. Once I start hitting the brakes (easy or hard) I see the "ABS Active" on the DIC. After about 1/2 mile I get all the lights come on the dash and the car turns off ABS and traction/handling.

I'm just at a loss as to what could be causing the problem. I know the tires have to be close to right rolling diameters but seems everyone uses this same setup without problems.

Today I threw the stock fronts on the car and drove around for a couple miles and the system did not freak out, no service warnings came on.

Any ideas or help would be greatly appreciated. I actually went out and bought new tires the other day just to see if the old tires were the problems (they were 265/35/18). No luck. Still same problem.

Thanks for the suggestions or idea.

Campfire

Stupid question but, were you programming the tire pressure sensors to the car on the CCW wheels? I ask only because I've run that wheel and tire package and had no problems. Well, my fronts are Michelin's but same size.

AngelSpeedFreak

Not a dumb question at all.

I do not have TMPS in the new wheels. I really don't see how that could be the problem but maybe it is?

It does not turn off anything with running stock tires in front and the 18's in the back. (Sensors in front, but none in the rear)

screaminchevy

Its the difference in tire diameter from front to rear. Those MT rears are about 27.5 inches tall. The fronts you have are only 25.8 inches tall. Hence your ABS and active handling going crazy. Get a front tire with less than 1in of difference from the rears and you'll be set.

Campfire

I wouldn't put it past the electronics in the car to freak out if it didn't see any wheel sensors but I certainly can't prove that it would. I'd try borrowing a tool from someone or swing by a tire shop to to have them do it and see what the results are. Here is a useful link on how to reprogram them with a tool:

http://www.corvetteonline.com/tech-s...nitor-sensors/

If you are in Houston, I'll be happy to help you out if you want to swing by my house.

AngelSpeedFreak

That is what I was thinking as well (even though everyone says they run exact size I have). But... When I put the stock fronts on, I have no probelms and those are smaller (285/30/19 so a 25.7 inch tall tire).

I'm just so frustrated at this point since I have already bought 2 sets of front tires. I really don't want to go buy a 3rd set and still have the same problem.

AngelSpeedFreak

thanks for the help. I bought these used off someone with a 2007 so unfortunately I now need to buy new sensors to work with my 2010. I'm okay with doing this once I figure out the problem, but I would be pretty sad if I go spend another $250 on sensors and install/balance and still have the same problem. The new tires I put on the front were $450 and didn't fix the problem. Feels like I am just throwing money at it with no idea what will work.

Campfire

I'm not suggesting the TMPS will fix it for certain but I am pretty sure my slicks are more than a 1" difference front to rear and I don't have any troubles. I'll try to grab a true measurement on them when I get home tonight to see verify the diameter difference.. Here is a photo of them sitting on my shop table, rears farthest from the camera. They are 305/650/18 and 325/710/18.

AngelSpeedFreak

Thanks Campfire. What are you using in the terms of spacer? Anything at all? I don't see how that could be my problem either as they spin fine but I'm grasping at straws now. It's frustrating.

thanks again.

screaminchevy

This is from my own experience. I had the same problem this year. A taller front tire to match the height of the rears fixed it. You need a 285/40/18R. I run a 295 on the front.

Campfire

I have a spacer for the fronts that I got from CCW. I'm really curious about this and will verify the height difference on the slicks, as well as check the Michelin's I have on the floor that came off the rims when I got the, with MT's on the back. Maybe I'm incorrect and they are all within 1" of diameter.

AngelSpeedFreak

I can see this could be the solution. I might just have to bite the bullet and order a 3rd set of tires. I see Tire rack has some 285/40/18 for about $300 shipped. Not too bad I guess. My mind just does not comprehend how the stock tires are working since they are smaller diameter than what I have on the 18s now. Then again, I don't know how many things in the world work and they just do. Thanks for your help.

Looking at stock sizes
Backs are 335/20/20 so 26.6"
Fronts are 285/30/19 so 25.7" - difference of 0.9"

My current setup:
Backs - 345/35/15 so 27.2"
Fronts - 285/35/18 so 25.9" - difference of 1.3"

I see the I am past the 1" difference mark. Just makes no sense if I throw the stock fronts back on to make a difference of 1.5 it works.

Campfire

I currently have no use for the Michelin's under my shop table because my only 18" rims are wearing slicks. The Michelin's I have are 285/35/ZR18's and worked just fine with the MT's. You could have them for a decent 6 pack of beer.

I'm just not sure why I wouldn't have problems if tire size were the culprit as my slicks have almost 2 1/2" difference in true diameter, as seen in the photo.

AngelSpeedFreak

Thanks Campfire, That is one hell of an offer and I greatly appreciate it. I don't think that your tires would do me much good as I currently have the same size though.

Do you happen to have a picture of the spacer you are using on the front? I ordered one from CCW but it has not come in yet. Maybe the 5mm spacer I'm currently using (made for corvette) is somehow messing up things? Guess my first step would be to wait for CC to ship the spacer I ordered.

Campfire

Here are pictures of one of the spacers. One for each side.

AngelSpeedFreak

Thank you Sir. Sure looks the same as what I already have, but at this point I'm just not sure what the problem could be so maybe this is it.

Thanks again for all the help. I will wait for my offical CCW spacers to arrive and (should be soon since I ordered a couple weeks ago) and if that doesn't work, sell the car.... lol

Texasthunder

It is definitely wheel height problem. The wheel sensors are calibrated for stock wheel height. It so happens that the difference on stock wheels is around one inch front to back. You can only go so much out of the calibration of the wheel sensor before the computer thinks something is wrong.


Wheel spacers have nothing to do with it.

AngelSpeedFreak

So think different cars just have different tolerances? Like how my car would not dyno the same numbers as another stock ZR1?

It's just odd that lots of people (including Campfire in this thread) have run the exact sized tires as I am with no problems.

Guess I just need to bite the bullet and order a 3rd set of front tires.

Anyone want to buy brand new 285/35/18's? Lol... Still have the sticker residue on them

Texasthunder

From what I have seen on this forum some cars seem to be more sensitive than others. You would more that likely get the same warning lights if you jacked up the rear of the car and run it (fronts on the ground). Because the rears would be turning and the fronts aren't the sensors would send this information to the computer and it would determine that something is wrong. Dynos have the same problem. Don't know how they get around it. You would be surprised at how intertwined all these sensors are. One sensor feeds information to another and so on.

AngelSpeedFreak

I never really thought about the fact that some cars would just be more sensitive but I can see that as being truth.

Even though lots of people have been able to run these tire sizes does not mean that everyone can. Also I guess all tires are not made exactly the same threrefore not all 285/35/18's are going to be exactly the same height.

Guess there is just no choice but to buy more tires

Thanks all for the help.