LT275/65R20 AT

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grizzstang

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I am thinking of moving up to this size from the stock 275/60R20's, I am at stock ride height with no level and no want to level but I have couple of questions.

1) How much of a power killer will this be? Given that they are 1 inch taller and 10 to 15 pounds heavier per tire. I have 392 gears but tow in the mountains.

2) Is recalibrating the tire size a necessity with a 1 inch increase in diameter? I know the speedo will be out a little but will the shift points be wacked and will I have other drivability issues?

3) Can the tire size be adjusted by any after market units like a ProCal since the PCM is locked?
 

WilliamS

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You can re calibrate the tire size easily with a programmer or AE tool if anyone is local.

You wont lose any appreciable power with 3.92's and only 1 inch taller tire.

275/60-20 is only 34 inches tall, will fit all day long.
 

GatheredEarth

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Not enough power loss to really be able to tell. You will have a couple miles per hour difference. Speaking from experience.
 

yortnodnarb

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I did the same thing with the same spec'd truck. Get a quickcal or something similar cause the shift points do feel better after calibrating. My average mpg before was 19.5-20 and after tires and level it runs 18.5-19. Only noticeable difference I can speak of is the ride quality dropped off slightly due to the 10ply tires.
 

AJAY

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I did the exact same thing you want you to do. The tires are heavier and stiffer but filled the wheel well nicely. I lost some get up and go. Also lost about .5 to 1 mpg after recalibrating tire size with a diablo tuner. Recalibrate as soon as you can because it readjusts your shift points and makes a difference when towing. I tow and haul in the mountains at time around 5 to 7,000 and going up is no problem. You'll notice more of a difference going down as the overall gearing of the truck changed along with the added mass of the tire. So you'll be braking more often. I ran Toyo Open Country ATII in LT275/65r20.
 

Yellow dog 55

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I am thinking of moving up to this size from the stock 275/60R20's, I am at stock ride height with no level and no want to level but I have couple of questions.

1) How much of a power killer will this be? Given that they are 1 inch taller and 10 to 15 pounds heavier per tire. I have 392 gears but tow in the mountains.

2) Is recalibrating the tire size a necessity with a 1 inch increase in diameter? I know the speedo will be out a little but will the shift points be wacked and will I have other drivability issues?

3) Can the tire size be adjusted by any after market units like a ProCal since the PCM is locked?
I’m in the same boat you are. Wondering if the weight or the height of the tire is going to have more effect on performance. I also like the 285/60/20 size (33.5x11.5) but they are also 16-18lbd heavier than stock.
 
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grizzstang

grizzstang

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^^^I have looked at those too but I think there are less to choose from and there wasn't much of a weight difference.
 
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