Do I need to change shift points on 09 A6 if I run drag radials?
 

I was all set to buy some C5 replica 17x9.5 wheels and a pair of 275/40/17 MT ET Street Radials for my 09 A6. Then I ran across some threads saying that this caused them to hit the rev limiter because it's 0.4" smaller in circumference than the stock tires. Does this happen to all C6 A6's? I have 2.56 gears, not sure if that makes a difference. I really don't want to do have a separate tune just for the dragstrip. Is there another drag radial wheel/tire combo that is close enough to the stock diameter?

Yes, with running a different tire size you'll need to definitely change your shift points.

There are tire sizes that are closer to your stock tires but I've run several different sizes (and types) of drag radials and contrary to popular belief, wider is not always better. I used to think that the MT ET Street radials were the best out there until I started running Hoosiers and wouldn't consider using anything else now. With Hoosiers not only do they hook better than the MTs, they will actually rehook if you don't get a good launch.

:iagree: Also hoosiers are the lightest drag radial out there. I cut 1.53 with stock 2.56 gears. The size I ran with the hoosiers were 315/30/18 and the tire had a diameter of 26.00. The stock runflat is 26.64, and thats why your really need to adjust your shift points.:)

Damn, there's no 26.4" drag tires? How do you switch the shift points at the track anyway, do you need your own hp tuners software and laptop? I didn't realize it was so much work just to run down the track occasionally. I don't want to void my warranty with a tune just now.

Yes the Mikey Thomspon dr's 305/30/18's have a tire diameter of 26.4 :cheers:

Sweet, what width wheels do people use for those? Do people use front C6 replica wheels?

Here is the link for the tires http://www.mickeythompsontires.com/s...StreetRadialII

If your going to run 18's, check out ebay.;) Or if you want drag wheels, CCW makes some of the best, but they cost.:)

Sweet, so people running these tires don't need to change their shift points or any other kind of tuning, correct?

:iagree: Except that they're actually 305/35/18. :yesnod:




Yes, you can use some 18" C6 replica wheels for those tires, 18x10 or 18x10.5 would be best but the 18x9.5 (that's the size 'jpee' uses with that tire) could work as well.

Cool, my only concern is that 305's may be *too* much traction for a stock converter and stock hp/torque? Like maybe it will bog too much and not allow enough spin?

It sounds to me that you've not yet been to the track. If you're bone stock, I'd suggest making a few passes to see if you really do need DR's. I ran 12.0's before the RF's weren't enough and had no issues at all when bone stock.

Actually I did and almost lost traction, which is why I want some stickier tires. You can read my post here:

http://forums.corvetteforum.com/c6-t...rip-today.html

After doing some searching on the forum, I found that other stock C6 owners also get squirrely on the 1-2 shift and they get drag radials just to solve this issue. Even if their 60 foot times don't improve.

OK, just read that and now recognize why you're researching DR's.

I do want you to know that same problem can exist with DR's, so it's not a guaranteed solution. With me it's finding the exact spot on the track where the earlier prep was dragged out a little more than where my shift point comes. I made 8 passes a week ago with MT DR's and had to back out of 4 because of excessive 2nd gear spin. This particular track only preps to about 200 feet on T&T days, so I nearly always spin at the shifts.

With only one pass under your belt, trying to make a decision what to do is difficult at best.

Is your car stock? Hmm, I thought drag radials would make it dead hook during the 1-2 shift. How on earth do these trailer queens I see get down the track with much more HP and gear?

Not stock any more, but when it was and even when slightly modded, I could still dead hook with the original non-Z51 RF's. My reason for using DR's is for more consistancy at the track that has poor prep. If I get out of the ideal track location I still spin on the 1-2 shift just like I would on the street with my Invo's.