Mounting wheels on DC Motor???

[FireRobot]

I am building a robot for a project I am working on and I need wheels for this robot.  The robot is going to weigh about 15 to 20 pounds.  I have two DC motors already which are the SD3757 brand found at this page:  http://www.transmotec.com/shop/SpurGear1W40W_SD37.aspx

I was wondering if anyone knew of where to find wheels for this motor.  I have searching everywhere but cannot seem to have any luck.  The diameter of the motor shaft is 6 mm, but it has a flat key which takes it down to 5.5 mm, so I would need a wheel that can fit very snug around this keyed shaft.  Also the wheels can't be foam.  I was thinking of rubber of some type.  If anyone has any suggestions of a good site for custom wheels or would know what a good solution would be that would be great.  The wheels I am looking for need to be about 3 or 4 inches in diameter.

Thanks,
Matt

[Ro-Bot-X]

Look on Lynxmotion's website for wheel hubs. Or on RobotMarketPlace.

[cooldog]

try
www.pololu.com

[Danish Boy]

well it is almost impossible to find a wheel, that fits on the shaft perfectly with the slot and everything. so my advise it to find a nice size wheel and buy a hub that fits(make them if you have machine access will save money).this will give you great results that will usually do the job.