front tire change on a C5?

[Highlander]

does it affect changing the front tire overal diameter with the C5?

[lplott]

Affect what?

I went from 17" to 18" and did not need to change anything.

If you are talking tuning, no, it doesn't affect anything.

Lonnie

[Highlander]

affect the active handling system vs the rear tires etc.

[lplott]

According to everything that I read before I went to the 4 wheel 18" setup, NO, the Active Handling will not be affected by doing the change in rim sizes. I tried very hard to keep the same wheel speeds when I went wider with the rear tires and finally decided to go with the Michilen Pilot Sport 335-30/18. There is only a 2-3% difference in tire circumference.

Lonnie

[ToplessTexan]

The EBTCM is the only thing that sees the wheel speed sensor inputs. If tire diameters don't change proportionally (or at least "close" to proprotional) you could see strange behavior out of TCS. You can't do anything through the PCM to prevent that. You might be able to influence how torque reduction requests are responded to be the PCM, but you couldn't do anything about application of brake pressure.