Racing Games are more popular category in P.C Games. I am dividing it here in 2 Categories.
Car Racing Games

Cross Racing Championship

a very interesting game and i hope it would give you great enjoyment.

  Genrally  Freeware Game 
        Free full version. Customize cars and race! Up to 6 players

Highway Pursuit Freeware Game
       Free Full Version. Like Spy Hunter, drive fast & shoot well!

Street Legal Racing Redline.

Create and race your own custom car!

Super Stunt Spect. Master death defying stunts for fame and glory!

Bike Racing Games

Trial Bike Basic 

     It is a new generation of Java games, as it contains realistic game play to which you can.t but become addicted. You are about to perform acrobatic feats riding a Trial Bike. Control both your bike and your rider. Challenging your ride try to make as less mistakes as it possible in order not to get error points. The less error points, the higher you get on the top list.

Furious Biker - Download Free Racing Game

Engine roar, wind noise in the ears, and hundreds of miles of the road up front – that’s all that a real biker needs. Always wanted to drive a heavy bike? Clothe leather jacket, gloves, western boots, and dart away along the highway? This is here now.

Moto Geeks - Download Full Version 

      The game Moto Geeks welcomes you to the world of breathtaking motor cycle races and formidable opponents. Various effects, splendid graphics and many fantastic routes will not leave you indifferent. You can choose one of the fastest superbikes and drive a race. Don't think it's so easy.

Trial Bike Ultra Game Download Full Version 

     If you enjoy motorcycles and you like to overcome obstacles, this is your game! Here you get a chance to test your motorcycle steering skills. Amazing realistic motion, complex obstacles, jumpsand all these are in full 3D! You need to be very cautious to take over all obstacles and keep your balance while cycling. You should go through a whole of motor track to get into a next level. A certain score is given for passing each level, and scores are dimishing with every second elapsed.