I am autox'ing my G35 frequently, so I've decided to buy a set of wheel with R-compound tires specifically for autox. I'm getting a set of the 18" OEM wheel and I was told on an scca forum that I can put 275-18" tires on the front and 285-18" tires on the back. Can anyone confirm this? This is assumed without rubbing.

 

that seems a bit too wide imo.... not saying it wont work but im guessing it wont.

 

oem 18s are 8 inches wide. widest you can go is 255 anything bigger you may be looking at problems

 

since you're going with R-compounds, you should be able to get away with a 265/40 but that's the absolute widest i'd go. Maybe better off with 255/45
-GP-

 

For some argument for and against going with wide tires on narrow rims see: https://g35driver.com/forums/autocross-road/132681-275-35r18-hoosiers-18x8-s.html. Ignore the inflammatory posts.

Are you limited to 8" wheels by rules? If not, I would just invest a little more and get wider wheels.

 

If you go too wide on a narrow wheel it's a waste anyway since some of the contact patch will be given up on bulge. I would stick with 255's.

 

Are the rims not 18x8 in the front and 18x8.5 in the back?

 

which wheel are we talkin about here? The OEM COUPE 18" wheels? if so, they are 18x8 all around, only the tires are staggered.
-GP-

 

Sorry, I should have been clearer.. hehe. Yes, they are the OEM 18" tires. Like these https://g35driver.com/forums/archived-sales/204173-18-stock-wheels-f-s.html