will 245/40/18 sized tire fit on a 18X9.5" wheel, or is the wheel too wide. I already have the tires and i wanted the 9.5 inch rims in the back for the deep dish style. I will eventually be moving up to 265 or 275 width tires in the future but will 245's fit for now?

 

Yes. I've had 245/40-18 Pirellis on my car for some time now, and I have Tein H-Tech springs that drop it about an inch all the way around... and I've had no clearance issues.

 

the stock rim is a 18X8" which will fit a 245 width tire fine, but what i was asking is if the 245/40/18 will fit on an 18X9.5" rim

 

it'd be close...personally i wouldnt do it, as the sidewalls wouldn't be perpendicular to the ground. check the manufacturers website for approved rim widths.

 

tire rack says that these tires that i have will fit any rim size within the range of 8-9.5". so i guess it should be alright.
http://www.tirerack.com/tires/Spec.jsp?make=Michelin&model=Pilot+Sport+PS2&vehic leSearch=false&fromCompare1=yes&partnum=44YR8SPORT PS2

 

Yes, always go to Tire Rack first for answers.

-Mr. Wigggles