First of all you NEED to tell us what car and or truck you are working on. Then what codes are setting. Maxisys can change some tire size. With out any more info you will not get any help.

 Maybe one  one of these? I searched Ronald McDonald Donk and there still is a lot of possibilities to pick from.

 Some gm's can can be reprogrammed for a different tire size. I am now sure on the corvette. I have done many gm trucks but the newer models do not offer size change. Look in the pdf file for functions. Tire size is usually located with tpms functions. The tool has no demo mode so without a corvette to hook up to I have no way to verify this. If I had to guess I would say maxisys probably can't do it. Look on the internet or call a friend at gm dealership. Hope this helps.

 Just curious.....is this some kind of drag racing car?  Did you change 2 tires or 4?

 From what I have read the stock front and rear tires are different sizes.
 
http://www.michelinman.com/US/en/tires/Chevrolet/Corvette/2015/Z06.html

The Rear are larger than the front and turn less revs per mile than the smaller diameter front tires. If you went with new rear tire with larger circumference that would reduce the rear revs per mile (for the rear wheels).Without reducing the rev per mile on the front (larger circumference)to keep the stock Rev per mile ratio  the same front to back, you might be F'ed because you would need to increase the front tire circumference to reduce the front rev per mile accordingly , but might not have the room to do so, unless you start cutting and Doggie Dog Donking  things :-)