Tire size calculations U7191 2006 Impala SS?

[corny40]

I went from 235/50-18 stock tires to 255/35-20 tires. The new tires are 0.7" smaller circumference which translates to being 0.8% too fast.

1) Should I adjust the tire size?

2) If/when I adjust it, can I just go in and adjust that parameter, or do I have to do it when writing a new tune to the car?

3) If/when I do adjust it, will it have to be adjusted eveytime a new tune is written or will it stay calibrated to the new size until I go back in and change it?

Thanks!

PS. I freakin' love this tuner. I still can't believe what it's done for my car, and I havent even started dialing it in yet.

[mikel]

1. This Predator does not support tire size adjustment.
If you want to recalibrate the speedo, we can do it for you in a custom tune, but I doubt it is necessary for such a small change.
2.Any time you adjust any parameter, you need to reinstall that tune so the modifications will take effect.
3.The changes you make will stay in effect until you restore the original backup, unless you choose 'reset parameters'.

Thanks