6l80 and smaller tires.

**11 6.2** · 10-26-2011 02:01 PM

So i wouldnt jack Justins thread im starting my own. Pretty much once i gt to where i need slicks i will need to get my tuner to set me up a seperate tune for the track so the truck will shift right? My stocks are 31.5 and the biggest M&H i have found it 29

**Frenchy** · 10-26-2011 02:05 PM

Yeah, you need re-tune. Just like you would ANY electronically controlled auto.

**Crazy Blu** · 10-26-2011 02:56 PM

Def retune on my spares I shift at 6400 no fun compared to 6800...

**CHEVROLADE** · 10-26-2011 08:23 PM

yup it will redline

**11 6.2** · 10-26-2011 08:46 PM

wow, this sucks..

**00Z71** · 11-02-2011 02:57 PM

Why does this happen? Are shift points set up by rpm?

**pl4yboy** · 11-02-2011 03:24 PM

Originally Posted by 00Z71

Why does this happen? Are shift points set up by rpm?

The truck must reach two requirements for the tranny to shift. One is MPH, the second is RPM. Now, you can zero out either table there and go strictly off the other, but in this case, it doesn't matter. If you put smaller tires on, the truck is going to think it's at a higher RPM than it is, because the tires revolve faster sending more VSS pulses. The truck needs to have tire size changed in the tune to correct for these pulses. If not, it'll short shift. Rob had a few problems with this at SAR last year because his slicks were so much shorter. He was shifting 500 RPM early.

**00Z71** · 11-02-2011 04:48 PM

Originally Posted by pl4yboy

The truck must reach two requirements for the tranny to shift. One is MPH, the second is RPM. Now, you can zero out either table there and go strictly off the other, but in this case, it doesn't matter. If you put smaller tires on, the truck is going to think it's at a higher RPM than it is, because the tires revolve faster sending more VSS pulses. The truck needs to have tire size changed in the tune to correct for these pulses. If not, it'll short shift. Rob had a few problems with this at SAR last year because his slicks were so much shorter. He was shifting 500 RPM early.

Weird since it is not meeting the rpm requirements... Wonder if it has to do with the speed limiter moved to calibration from GM

**1BadCC** · 11-02-2011 06:57 PM

Can you put the slicks tune on the tow haul? Were you can have your stocks on and everything be normal. Then click the tow haul on once you put the slicks on

**George C** · 11-02-2011 07:13 PM

not correctly

Originally Posted by 1BadCC

Can you put the slicks tune on the tow haul? Were you can have your stocks on and everything be normal. Then click the tow haul on once you put the slicks on

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6l80 and smaller tires.

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