I run 555R at 315X35 & 245X40. The R tire has high traction 100 treadware rubber & the G2 has 200 treadware & with the high speed compound 320 treadware.
NITTO lists & treats the G2 as a "summer" tire & the R as a "competition" tire.
In practical terms the 555R puts my car in the Pro XP Class...