Tire Size Questions

[MPG-HAHA]

I am contemplating changing the Goodyear RSA 265-60-17 to maybe a 265-70-17 on my 2011 PPV Tahoe 77k miles. The sad thing I just put a brand new one as my spare...
I have read multiple threads on the fit is no problem and other than the MPH offset , they fill the wheel wells nicely.
So the questions are :
Is it required to get it tuned or run it stock as is for the tire size change for normal driving other than watch your speed?
And at highway speed 65-70 is the transmission hunting between 5th and 6th noticable and / or will it damage the transmission or other items?
It's not daily driven and occasionally driven on the highway, just want a smoother ride.
Thanks

 

[mikez71]

Not enough difference to matter..
Also your shift schedule is exactly like a stock tahoe, EXCEPT for a few mph due to the tire difference..
Since the ECM thinks you're going slower than you actually are, you will probably shift at the same speed as a regular tahoe anyway?
(just that indicated will be a few mph slower)

That said, a tune can greatly improve, if not eliminate, the hunting you normally experience..

 

[Marky Dissod]

Tune is not required, just very strongly advised, but not because of the speedo error.
265/70R17 will not damage or even prematurely age the transmission - what does that is failure to get tuned.
For the price difference between 265/60R17 vs 265/70R17, find a human who will tune your ecm & tcm to suit your vehicle & how you drive it.