[Obzen]

to be fair. The stock tires are two different profiles. 40 in front 35 in rear.

[MatthewAMEL]

Originally Posted by Obzen

to be fair. The stock tires are two different profiles. 40 in front 35 in rear.

Learn something every day.

[Doyal_Mcneff]

Originally Posted by ender2664

265/35 upfront and 305/30 in the rear. Why would the rim matter when the tire determines the height?

Because a 265 is a pretty bad choice for a 10 inch wide rim.

[Doyal_Mcneff]

Originally Posted by ender2664

Why wouldn't you mix profiles?

There's nothing wrong with mixing profiles. Its when you mix profiles and the rear is shorter than stock, your going to run into issues, because your rear wheel speed is moving faster than your front which will make tc kick in early. You might not feel it because you probably don't drive our car hard.

[Doyal_Mcneff]

Originally Posted by MatthewAMEL

Could be wrong here, but the ECU uses tire rotation speeds (as they relate to each other) for adjustments.

If the fronts are constantly rotating at a different speed than the rear, it could cause weird issues.

Exactly!...and it's very noticeable when the rear is shorter than the front tire in relation to the oem stagger. The tolerance for front wheel speed moving faster than the rears are much greater than the rears moving faster than the fronts. This is how traction control senses when your rear wheels are slipping.

[Doyal_Mcneff]

Originally Posted by Obzen

to be fair. The stock tires are two different profiles. 40 in front 35 in rear.

Yep and tc is tuned to that stagger. Rear wheel speed is very sensitive to changes. That's why I always recommend going taller in the rear but staying within 2% of the original stagger. My set up puts me at 1.5% and I have no tc issues. I did have issues with a 275-35,305-30 set up. If you put around, it's not an issue, but if you actually drive the car it's very noticeable unless you turn tc off.

[ender2664]

Originally Posted by MatthewAMEL

Could be wrong here, but the ECU uses tire rotation speeds (as they relate to each other) for adjustments.

If the fronts are constantly rotating at a different speed than the rear, it could cause weird issues.

The stock ones rotate at a different rate front to rear.
using a different AM profile gets the delta much closer to stock.

[JBinSD]

Enders, have you observed any TC issues going with the 275 35 up front, and 305 30 in rear? my rims will be 10's and 11's, but I don't think that effects the ride height or rotation at all.

[Doyal_Mcneff]

Originally Posted by ender2664

The stock ones rotate at a different rate front to rear.
using a different AM profile gets the delta much closer to stock.

Yes....that's the .1 stagger. The bottom line is your tc will kick in earlier than it did with oem tires. Whether you push your car enough to realize it, it kicks in.

[ender2664]

Originally Posted by JBinSD

Enders, have you observed any TC issues going with the 275 35 up front, and 305 30 in rear? my rims will be 10's and 11's, but I don't think that effects the ride height or rotation at all.

I have not noticed any issues at all but never use tour or sport modes so I cannot tell you if those are affected them. Track and comp only for me.
I don't take the car to its handling limits but do to its straight line...no difference in a straight line. None at all.

[Doyal_Mcneff]

Originally Posted by JBinSD

Enders, have you observed any TC issues going with the 275 35 up front, and 305 30 in rear? my rims will be 10's and 11's, but I don't think that effects the ride height or rotation at all.

It will effect both. A shorter tire is shorter which effects ride height, and a shorter tire spins faster than a taller tire.

[ender2664]

Originally Posted by Doyal_Mcneff

It will effect both. A shorter tire is shorter which effects ride height, and a shorter tire spins faster than a taller tire.

Not sure what u r doing to your car but I experience no difference.

[Doyal_Mcneff]

Originally Posted by ender2664

Not sure what u r doing to your car but I experience no difference.

Ok...did you read his post? He said he didn't think it would effect ride height or rotation. When in fact it effects both. Is a shorter tire shorter? Does a shorter tire spin faster? So...yes...a shorter tire will effect rotation and ride height.

A 305-30 will drop the car .2 inches lower to the ground and increase the wheel gap by .2 inches. And it rotates 13 more times per mile than the stock rear.

[JBinSD]

Eagle F1 supercars 305/35/20's are $254,http://www.tirerack.com/tires/TireSe...earDiameter=17
if I'm using the stock rears up front, would this be a better rear? I'm running 10's and 11's, LE1 reps. . .