what size tire should I run on 18x10 1/2???

I want to go with some nitto 555 drags but not sure what size to go
with ? I have some c6 rims that they will be going on, I just need a
size for the rear 18x10 1/2. Thanks for any help from you all.

ZeeS,

295/30/18 or 295/35/18's

I want to go with some nitto 555 drags but not sure what size to go
with ? I have some c6 rims that they will be going on, I just need a
size for the rear 18x10 1/2. Thanks for any help from you all.

If I read this correctly, you are interested in the 555R drag tires. That limits you to the 3 sizes Nitto makes in the 555R line, and only the 285/35-18 (25.91") or the 305/35-18 (26.42") will fit your car. The 305/45-18 is over 28" diameter.

Both those tires will work with 10.5" wide wheels. Whether the 305's will rub excessively with the deep offset of the Z06 wheels is another question.

305s on the 10.5 Z06 here.