Most realistic PC racing sim?

I searched through the forums and didn't find a thread on this...surprisingly...so here it goes:

I like simulators and I'm about to get a steering wheel so I was going for a racing sim to go with it. I'm wondering what the most realistic one was in the sence of vehicle behavior, parts tweaking and graphics. I'm currently deciding between RACE the WTCC game and GTR2, but I know there are many others. I know Live For Speed is supposed to be very realistic but it's on-line only.

Can sim enthusiasts help out?

P.S. I don't want this to turn into game wars "This is better" "No, this is better". I'm looking for supportive arguments.

I haven't played the new one, but I had the original GTR and it is by far the most 'accurate' simulation that I have played, at least in terms of recent releases (Grand Prix Legends is older but also very tough).

 The sheer variety of options is impressive, graphics are great and the learning curve can be as steep as you want.  Don't imagine you could do wrong with the new one tbh.

Thanks, seems like Rfactor is a really good choice. I'm amazed it only has 100 or so reactions and no Gamespot review (aparently they don't import games from EU to review them).Jedo

Gamespot overall almost completely ignores downloadable games, which is sad, because they are becomming bigger and bigger part of pcgaming with each year 

GTR2 if you're looking for GT racing... it also comes with GT Legends which is really cool retro club racing style stuff, also with a very realistic racing model.  SimBin is coming out soon enough with an F2000 sim that will be bundled with RACE, so watch out for that too.