I took my 08 base A6 to the track last night. First chance at running it since putting a set of Firestone Firehawk Indy 500s on the car to replace the factory Goodyear RFs. These seem to perform much better than the GYs on the road and also hooked much more consistently at the track.

The weather is still too warm for great passes here and the temp was in the low 70s even late at night and it was humid.

My times and speeds puzzled me. I was putting up much better trap speeds at the 1/4, topping at 119.59 versus a previous best of 117.22. However, my best time was a 12.33, which is off of previous runs. Also, my 1/8 trap speeds were lower by 1-2 mph than normal even though my 1/4 traps were higher by 2-3 mph. My 60 ft. times were consistently 2.03-2.08. Also, on the one run where 1/8 mile trap speed was over 91 compared to 89 on the others, my 1/4 trap was lower at 116.7 versus 118-119 on the other three runs. That run was the only one done in competitive driving mode and in the right lane versus the left lane.

Also, from this and previous runs, my car doesn't seem to run as well in competitive driving mode as it does when I just turn the traction system off.

Finally, does just changing the factory OEM tires to another set of street tires disqualify me from posting in the factory stock class on the 1/4 mile performance thread?

Thanks to any that take time to read and answer.