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      11-11-2012, 06:17 PM   #29

Drives: 2011 335d
Join Date: Aug 2012
Location: MidWest

iTrader: (0)

hotrod, I would appreciate any feedback from your extensive drag racing experience regarding my tire question from post #16.

"Question regarding tire size from a dragsrip newbie for those more experienced:

Used 245/45R17 Hoosiers which have a 26.2 in diameter (correction, it's 26.0 based on the manufacturers website). This is significantly larger than stock wheel size and pushes the 4th-5th shift up to ~111mph. Thought this would be high enough that the car wouldn't waste time shifting into 5th during the pull, and more than make up for the slower acceleration at the beginning from the larger tires. However, looking at the recording of the pull (used the Track Recorder option the Android Torque app, and overlaid rpm data on the display) it shows the car was going a bit faster than anticipated and did the 4th-5th shift just before crossing the finish line. So the car was just getting into 5th gear as it went through the trap and finish line.

Would it be better to move to a lower diameter tire and have the 4-5 shift occur before the trap, so the car isn't coasting through the line, and also get better starting acceleration? Or is the larger diameter tire a better option?

Any insight for a 1/4 mile newbie would be appreciated.