Different shift points with 17" tires?
Thread Starter
Melting Slicks
Joined: Sep 2004
Posts: 3,287
Likes: 1
From: Union City CA
Different shift points with 17" tires?
This question is for people with A6 and 17" Drag radials.
I am just wondering if replacing my 19" with 17" drag radials for the the track, would the shift point change? I am worried that when driving in S mode and letting the car shift itself at the track, would the shift change so it would go over the limit since the rear tires are now 17"? Any feedback from drag racers would be appreciated.
I am just wondering if replacing my 19" with 17" drag radials for the the track, would the shift point change? I am worried that when driving in S mode and letting the car shift itself at the track, would the shift change so it would go over the limit since the rear tires are now 17"? Any feedback from drag racers would be appreciated.
Drifting
Joined: Nov 2005
Posts: 1,745
Likes: 35
From: Turlock CA
This question is for people with A6 and 17" Drag radials.
I am just wondering if replacing my 19" with 17" drag radials for the the track, would the shift point change? I am worried that when driving in S mode and letting the car shift itself at the track, would the shift change so it would go over the limit since the rear tires are now 17"? Any feedback from drag racers would be appreciated.
I am just wondering if replacing my 19" with 17" drag radials for the the track, would the shift point change? I am worried that when driving in S mode and letting the car shift itself at the track, would the shift change so it would go over the limit since the rear tires are now 17"? Any feedback from drag racers would be appreciated.
--Dan
Le Mans Master
Joined: Feb 2006
Posts: 5,762
Likes: 4
From: Chandler Arizona
I just put on some 275/40-17 Nitto drag radials and I haven't noticed a difference. Your shift points are based on both engine rpm and vehicle speed. But since the vehicle speed is picked up off the ring gear of the diff, it shouldn't make any difference as far as the size of the tires.
However, Dan points out that the drag radials must grow since both have the same revs per mile. Either way, you should be fine and my recent experience says it works.
However, Dan points out that the drag radials must grow since both have the same revs per mile. Either way, you should be fine and my recent experience says it works.
Le Mans Master
Joined: Sep 2004
Posts: 5,707
Likes: 4
From: Los Angeles
Wide open throttle shift points are determined by engine redline ONLY. THey don't care what speed you are going. Furthermore, a 17" vs a 19" wheel makes absolutely NO difference. That's the diameter of the WHEEL, NOT the TIRE! You can buy tires in all kinds of diameters to fit any size wheel you want. It's the OUTSIDE diameter of the TIRE itself that makes the difference NOT the WHEEL diameter. That's why you have 25, 30, 35, 40 and 45 series tires to choose from. For your everyday driving you want the OUTSIDE diameter of the tire to be the same as the original OEM tires for the sake of traction control, active handling, abs and speedometer. So the TIRE size is what you want to compare. NOT the WHEEL size. 
Thread Starter
Melting Slicks
Joined: Sep 2004
Posts: 3,287
Likes: 1
From: Union City CA
Wide open throttle shift points are determined by engine redline ONLY. THey don't care what speed you are going. Furthermore, a 17" vs a 19" wheel makes absolutely NO difference. That's the diameter of the WHEEL, NOT the TIRE! You can buy tires in all kinds of diameters to fit any size wheel you want. It's the OUTSIDE diameter of the TIRE itself that makes the difference NOT the WHEEL diameter. That's why you have 25, 30, 35, 40 and 45 series tires to choose from. For your everyday driving you want the OUTSIDE diameter of the tire to be the same as the original OEM tires for the sake of traction control, active handling, abs and speedometer. So the TIRE size is what you want to compare. NOT the WHEEL size.
Safety Car
Joined: Nov 2007
Posts: 4,537
Likes: 1,404
From: Bethesda MD
I know that drag radials can grow, but my experience with nittos is that they grew much less than a slick, and a 35 sidewall doesn't have much give either.
Tech Contributor
Joined: Jul 2002
Posts: 14,950
Likes: 266
From: St. Louis, MO
St. Jude Donor '08
I run the MT 17" drag radials. They absolutely cause your speedometer to read about 3 mph fast, verified by my buddies pacing me in the way to the track.
They dont affect my shift points, dunno if they will affect an automatics.
They do give you a nice gearing advantage that was worth about .10 in the 60 ft.
They dont affect my shift points, dunno if they will affect an automatics.
They do give you a nice gearing advantage that was worth about .10 in the 60 ft.
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Safety Car
Joined: Aug 2006
Posts: 4,206
Likes: 6
From: Makena, Maui & NM
I just put on some 275/40-17 Nitto drag radials and I haven't noticed a difference. Your shift points are based on both engine rpm and vehicle speed. But since the vehicle speed is picked up off the ring gear of the diff, it shouldn't make any difference as far as the size of the tires.
However, Dan points out that the drag radials must grow since both have the same revs per mile. Either way, you should be fine and my recent experience says it works.
However, Dan points out that the drag radials must grow since both have the same revs per mile. Either way, you should be fine and my recent experience says it works.
Last edited by siffert; Dec 22, 2007 at 09:46 PM.
Safety Car
Joined: Nov 2007
Posts: 4,537
Likes: 1,404
From: Bethesda MD
Tech Contributor
Joined: Jul 2002
Posts: 14,950
Likes: 266
From: St. Louis, MO
St. Jude Donor '08
Why P275/40-17 (25.63 OD, 10.91 OW, 1433 LR, 811 Revs Per Mile) instead of say 315/35R-17 (25.79 OD 12.13 OW, 1874 LR, 806 Revs Per Mile)? Is it the higher load rating or too wide? Would you put Nitto's on the fronts or just stick with oem fronts? What 17" wheel would you use? I figure one would not use tire sensors on them, but how does that effect the DIC or computer?
I run stock tires up front and no sensors in my drag radials. I use C5 front wheels I had from my old C5. They fit fine, been using them for years. Most use C5 Z06 front wheels which are an inch wider. My track is 80 miles away, sometimes I get a DIC message on the rear sensors missing about 60 miles in and sometimes I don't. If I get the message I can't select Comp Mode, just traction control on or off. But it doesn't seem to affect anything else (that said I have Torque Management and traction control tuned out anyway).
Safety Car
Joined: Aug 2006
Posts: 4,206
Likes: 6
From: Makena, Maui & NM
The taller sidewall of the 17" is better, it absorbs more of the shock of launching as opposed to breaking traction or rear ends. A taller sidewall gives more "wrinkle". Kind of a marginal benefit with drag radials though. The real benefit is the Mickey Thompson compound, it is very sticky tried and true. My buddy was cutting 1.4's on his all night last night and he's got a C5 Z06 with a 6 speed.
I run stock tires up front and no sensors in my drag radials. I use C5 front wheels I had from my old C5. They fit fine, been using them for years. Most use C5 Z06 front wheels which are an inch wider. My track is 80 miles away, sometimes I get a DIC message on the rear sensors missing about 60 miles in and sometimes I don't. If I get the message I can't select Comp Mode, just traction control on or off. But it doesn't seem to affect anything else (that said I have Torque Management and traction control tuned out anyway).
I run stock tires up front and no sensors in my drag radials. I use C5 front wheels I had from my old C5. They fit fine, been using them for years. Most use C5 Z06 front wheels which are an inch wider. My track is 80 miles away, sometimes I get a DIC message on the rear sensors missing about 60 miles in and sometimes I don't. If I get the message I can't select Comp Mode, just traction control on or off. But it doesn't seem to affect anything else (that said I have Torque Management and traction control tuned out anyway).
Thanks much for the info! So no problemo's fitting and drag racing 275/40's on 17 x 8.5 wheels as opposed to 17 x 9.5 wheels? Those wagon wheels seem easier to find than the Z06 wheels.
Tech Contributor
Joined: Jul 2002
Posts: 14,950
Likes: 266
From: St. Louis, MO
St. Jude Donor '08
