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Discussion Starter · #1 ·
I was reading about the 2006 6-speed transmission and they were saying that if you alter the wheel height, during towing it would not shift into 6th gear... Is the correct? I was looking at getting 33" and after reading it I wanted to know if anybody has ran into this problem.
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Discussion Starter · #3 ·
I got this from the allisontransmission.com from the FAQ
Q. Speedometer / Tires - What effects will big tires have on transmission operation? A. The TCM calibration is based on factory tire size and rear axle ratio. Changing either of these parameters will have some adverse impact on transmission operation, including features like grade braking and shift stabilization. For instance, we have noted that when P285 tires are installed that the transmission generally does not shift to 5th range when towing heavy loads.
 

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I got this from the allisontransmission.com from the FAQ
Q. Speedometer / Tires - What effects will big tires have on transmission operation? A. The TCM calibration is based on factory tire size and rear axle ratio. Changing either of these parameters will have some adverse impact on transmission operation, including features like grade braking and shift stabilization. For instance, we have noted that when P285 tires are installed that the transmission generally does not shift to 5th range when towing heavy loads.
The tranny does have to work mechanically harder because of the loss in leverage from the taller tire.

I put 285's on my truck within a week of getting it, and 5th gear is all I tow in. I think others will tell you thats not an issue.

If you towed really heavy, then it might tend to go to 4th more looking for gearing help, but add a tuner and you then have plenty of power to pull in top gear.

.
 
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