99 c5 tire size current says 87.48?
 

Cant figure out why the tire size is this high. Shifting and speedo are accurate, but if i put in 25.6 for a 275/35/18 then all is wrong. I have no idea where this number came from. Anyone have any idea?
https://cimg6.ibsrv.net/gimg/ls1tech...3aee17e444.png

Has anyone else looked at the file and does your show the same thing?

Best i can figure this is close to the circumference. 87.48/3.14 =27.85 tire hieght. 25.6 tire would be 80.38 Maybe it has something to do with the new updates to HP Tuners. I haven't tried changing the tire size on any other vehicle to test.