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New Rims and Tires = VERY Sluggish... even with BB tune

agrats84

By agrats84
in Tires, Wheels & TPMS

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agrats84 Enthusiast

agrats84

Posted
Posted

Two months ago I put on new rims and tires. I had stock 18" rims and 265/65 tires. I put on the GMC 20" rims with Zeon LTZs 275/60s. I had a BB tune and had Justin retune it for the larger tires. It still feels completely underpowered and very sluggish. I just hit 36K miles and had a major service done at 30K so I'm confident its simply the larger tires and how it shifts. The rest of the truck is stock. Most of my driving is single lane roads between 40-50mph and it has a very hard time finding the right gear.

 

Is there anything I should be looking for/ cleaning that could cause this? I've read about the MAF sensor but don't know if I should go messing around with it.

 

Thanks and Merry Christmas!

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2010LTZ4x4 Enthusiast

2010LTZ4x4

Posted
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I wouldn't blame the tire size for the sluggish performance, there isn't enough size difference between the old and new for that.

MikeNH Senior Enthusiast

MikeNH

Posted
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Tire size no, but rim size for sure. Those 20s surely weigh a bunch more than 18s.

2010LTZ4x4 Enthusiast

2010LTZ4x4

Posted
Posted

How about checking with Justin to see if he missed something?

I don't have a tune but I do know how they work, and he might of entered a wrong value some where in the program.

DB_1 Enthusiast

DB_1

Posted
Posted

A lower gear ratio would help. If you're at 4.10 already next lowest would be 4.56 which might be a bit much though.

Major_Kong Enthusiast

Major_Kong

Posted
Posted

I would guess that the new wheels & tires are the problem. I changed wheels & tires on my car a few years back and immediately noticed that acceleration was a bit slower and braking was diminished. Have you tried to put the stock wheels & tires back on to see if there was still a performance problem?

agrats84 Enthusiast

agrats84

Posted
  • Author
Posted

I have the Autocal so I never swapped out the PCM. I tried putting it back to stock and it feels no different. Maybe it is the tune and Justin can modify it. Hopefully that's the answer.

5829BMG Enthusiast

5829BMG

Posted
Posted

Had the same issue when I changed rims and tires. Almost took them off because of it but I've gotten use to it and the truck seems fine now.

agrats84 Enthusiast

agrats84

Posted
  • Author
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I don't even know what that means. I'm open for any possibility of what it could be and how to improve it.

 

Is that something I go through Justin with or can I do it myself?

jdubub Senior Enthusiast

jdubub

Posted
Posted

A crank relearn is not necessary with the Autocal because you are not changing the ECM, just modifying it.

Zembonez Senior Enthusiast

Zembonez

Posted
Posted

IF the new wheel and tire combo is a lot heavier (those Coopers are heavy) you can expect quite a difference in feel and even a drop in fuel economy. I know I lost about 1.5 mpg when I went to 20s on my truck... and I went with a pretty light tire and wheel combo. The Zeons are heavy tires.

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