I can check.

It's a moot point,the car can not tell when you have changed tire size therefore the tuner can not pull the new tire size information from the car. The car has to be told what the tire size is.

 

The tuner only reports what is set in the controller. The controller (and thus the tuner) doesn't autosense a tire size. This info is manually put into the controller. The 27.25 reported by the tuner is the correct rolling diameter for your original tire (28.18 overall diameter) and was set at the factory. Your new tires have a smaller rolling diameter and needs to be changed with the tuner to match. Since sidewall stiffness varies between tire brands and model and profile, if would be extremely difficult to guess what the correct number would be without measuring.

You are looking at a 3.3% difference in overall tire diameter. All else being equal, this would be equivalent to changing your gears from 2.82 to 2.91 - not a big change. Since lower profile tires usually have stiffer sidewalls, your rolling diameter difference is probably even less than that. You report your 0 to 60 times have gotten better (about a 5 % improvement). Stickier rubber may have been a big factor here.

Have a safe and happy holiday.

Redbeard