Using Mich 285/30/19 on C6
Thread Starter
Racer
Joined: Jul 2007
Posts: 363
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From: Houston, Texas
Using Mich 285/30/19 on C6
I put these Mich PS2 285/30/19ZR from what I believe is the front tire from a C7Z on the rear of my C6. While they are nice and sticky and handle well, I noticed my "traction control engaged" alert has come on a number of times. Particularly when I am going up a fair steep hill. Anyone thinks these tires cause a problem and why?
Race Director
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Yep, the front tires need to be 1.04" smaller OD than the rear tires.
Hence the car has sensors for the speed of all four tires at the wheel hubs that is calibrated for the 1.04" tire size difference front to back, and when the front to back tire size ratio is wrong, the car is going to throw all kinds of codes since it not seeing the front and back tires covering the same amount of ground.
Hence the car has sensors for the speed of all four tires at the wheel hubs that is calibrated for the 1.04" tire size difference front to back, and when the front to back tire size ratio is wrong, the car is going to throw all kinds of codes since it not seeing the front and back tires covering the same amount of ground.
Intermediate
Joined: Jan 2014
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Yep, the front tires need to be 1.04" smaller OD than the rear tires.
Hence the car has sensors for the speed of all four tires at the wheel hubs that is calibrated for the 1.04" tire size difference front to back, and when the front to back tire size ratio is wrong, the car is going to throw all kinds of codes since it not seeing the front and back tires covering the same amount of ground.
Hence the car has sensors for the speed of all four tires at the wheel hubs that is calibrated for the 1.04" tire size difference front to back, and when the front to back tire size ratio is wrong, the car is going to throw all kinds of codes since it not seeing the front and back tires covering the same amount of ground.
Race Director
Joined: Dec 2013
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40 front/35 back, 35 front/30 rear does not matter with the ECM, so long as the front to rear tire diameter difference is close to needed 1.04" differences.
Here is a tire calculator that you can input your front and back tire numbers to check to make sure that the tire size front to back diameters are close to being correct.
http://www.discounttire.com/dtcs/infoTireMath.do
Hence if you are running 245/40/18's on the front, and 285/30/19's on the rear, the tire diameters of the two against each other are way off . You would need to change out the front tires to 245/35/18 instead.
As for the smaller side walls tires, mixed blessing really.
The smaller the side walls, the less side wall flex and the better they are going to cornering.
The cons to smaller side walls, less defection in the tire sidewall to absorb bumps and could lead to a bent rim on bumps faster also the less flex the side walls has, the worse for acceleration dig out from a dead stop as well.
As for road coursing the vet on the stock base width rims, the widest you can get away with is 255/35/19 on the fronts, 295/30/19 on the rears without problems or the tires ballooning on the rims (.094 difference).
Note, 255/40/18F and 295/35/19R works as well.
Here is a tire calculator that you can input your front and back tire numbers to check to make sure that the tire size front to back diameters are close to being correct.
http://www.discounttire.com/dtcs/infoTireMath.do
Hence if you are running 245/40/18's on the front, and 285/30/19's on the rear, the tire diameters of the two against each other are way off . You would need to change out the front tires to 245/35/18 instead.
As for the smaller side walls tires, mixed blessing really.
The smaller the side walls, the less side wall flex and the better they are going to cornering.
The cons to smaller side walls, less defection in the tire sidewall to absorb bumps and could lead to a bent rim on bumps faster also the less flex the side walls has, the worse for acceleration dig out from a dead stop as well.
As for road coursing the vet on the stock base width rims, the widest you can get away with is 255/35/19 on the fronts, 295/30/19 on the rears without problems or the tires ballooning on the rims (.094 difference).
Note, 255/40/18F and 295/35/19R works as well.
Last edited by Dano523; Dec 19, 2015 at 01:42 PM.
Team Owner
Joined: Mar 2008
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From: Southern Utah
An easy way to get the right tire size is to use the "revs per mile" spec for the tires, which is shown on Tire Rack's site. Calculate the F/R ratio for the stock tire sizes and then apply that to the set of tires you have....this will give you a revs per mile target for the other tire set.
Thread Starter
Racer
Joined: Jul 2007
Posts: 363
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From: Houston, Texas
Thanks all for some good info. I have been driving with traction control off to stop the nanny alerts. It hasn't given me grief handling wise I just want to make sure I am not destroying something! I may switch back to 35's because they don't make a 245/30/18 in runflat.
Race Director
Joined: Dec 2013
Posts: 12,502
Likes: 3,631
Thanks all for some good info. I have been driving with traction control off to stop the nanny alerts. It hasn't given me grief handling wise I just want to make sure I am not destroying something! I may switch back to 35's because they don't make a 245/30/18 in runflat.
Hence general rule 40F/35B, 35F/30B, or 30F/25B, to end up with the 1.04" rear tire larger OD difference when you have 18"F/19"B, or 19"F/20"B combo's.
Last edited by Dano523; Dec 22, 2015 at 03:24 PM.
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Thread Starter
Racer
Joined: Jul 2007
Posts: 363
Likes: 4
From: Houston, Texas
Sorry, that was a mistake. I meant 245/35/18's on front. I found they do have a 255/35/18 but then there is the question of will it clear the wheel wells and fit the wheels properly. Sounds like a bunny hole I don't want to go down!