I just picked up a set of 17 in GTO wheels and stumped on tire size
Should I go with 255-45-17 or 2455-40-17 on all four wheels.

 

275/40/17 with a 2.5in spacer should be nice

 

I would go 245-45-17 as the wheels are not wide enough for 275 tires and 255 has less choices to pick from...

 

gto rims are 17x9s no? in the case of 17x8s then yes paul is right

 

Wheels are 17-8 not 17-9. Wish they where 9 inch wide. That's why I'm leaning towards 245-45-17 on all 4 wheels. The offset is 40mm which means I'll need 1.25 inch spacers

 

you want the offset as close to 0 as possible. you would ideally want a 40mm spacer which is 1.5748 inchs. i thought GTO wheels were 4th gen fbody specs. 17x9 +56mm. so disregard my first post.

i would go with the 245/45/17 and the 1.5inch spacer