I recently had an unnamed shop stagger my tires on my c6 the wrong way. My front tires were an inch bigger than the rears...... TCS problems of course. My question is: does the front to rear tire ratio have to be greater than 1.31 inches bigger inthe rear? I'm hoping that just bigger in the rear will work. I crunched the tire size diff. and it comes out to 1.31 (i think) bigger in the rear. The tires that the shop ordered to replace the bass akwards front tires will make the rears .6 of an inch bigger. WIll this keep my TCS happy? My fear is that it will work at lower speeds, but the ratio will have a greater effect at much higher speeds.
TIA

 

ttt

 

>I recently had an unnamed shop stagger my tires on my c6 the wrong way.

"Had" them stagger? On purpose by your design? or mistake by the "unnamed" shop?

>My front tires were an inch bigger than the rears...... TCS problems of course.

Of course.

>My question is: does the front to rear tire ratio have to be greater than 1.31 inches bigger inthe rear?

Are you talking about overall diameter of the installed wheel/tire combo?

>I'm hoping that just bigger in the rear will work.

Hope is good, but probably not an adequate subsitute for knowledge.

>I crunched the tire size diff. and it comes out to 1.31 (i think) bigger in the rear. The tires that the shop ordered to replace the bass akwards front tires will make the rears .6 of an inch bigger.

I think that you need to use a proper tire diameter calculator to see what would work for whatever purpose you have in mind.

>WIll this keep my TCS happy?

The TCS is calibrated for the stock tire sizes. Any deviation will result in some sort of compromise.

>My fear is that it will work at lower speeds, but the ratio will have a greater effect at much higher speeds.

Probably correct, given that the effects at higher speeds are probably more consequential.

Let's start again by giving us some hard details: The wheels sizes front and rear (before & after). The tire sizes front and rear (before & after). Make of wheel. Make of tires. Purpose of the modification.

 

Stock diff in size is 1.31 inches in diameter bigger in rear. The guy at the shop staggered them backwards by accident. I took he car home at night when i didn't notice the massive mistake. The difference in size I'm hoping o go with is .6 inches bigger in the rear. The purpose is to put a much wider tire under the car. Stock rims. I'll get the exact tire sizes later today.

 

I am running viper tires in the rear (345/30/19) that are 27.4" in overall diameter without any problems whatsoever.

 

From when I had my C5, I'm assuming the C6 will be the same....

As long as the rear tire diameter is the same or larger than the front, TCS should be content. If the fronts are larger it will NOT be happy.

Something else to consider is the accuracy of the speedometer. Unless you get a custom tune or handheld programmer to adjust it, you'll be slightly off. If you don't change the programmed size you can still calculate the difference in the old/new tires and the % difference will be the same in your speedo. Then while you're driving down the road you'll just have to remember your a few MPH off.

 

The TCS can be adapted to run any size tire, on any corner of the car with a change in the tire diameter entry in the PCM. HPtuers does this by simply entering the rear diameter only. If you increase the size of the front tires, then you input a smaller value for the rear so it knows the rotational relationship.

I found this out when my rear tires wore so significantly on my C5 that the TCS was reading the rotational increase in speed of the rear tires as a loss of traction. I input a smaller diameter for the rears and it was fixed. The Z06 for the C5 had smaller diameter rears than the coupe and had reflected this in the stock factory PCM entry.