Mounting wheels to any DC motor ?

Hello everybody!

I am familiar with electronics and I have made a few small robots (obstacle avoidance robot; light tracking robot; robot which follows a person with IR pulsing emitter in his hands;...). But I have done it with small,cheap dc motors available on ebay, the wheels were included.

Now I want to make a robot which can drive around 5 to 10kg, so all I need are better, more powerful motors. But most of the available dc motors do not include wheels. I don't know how to be sure that the wheels will fit the dc motor. I am not confident after reading the specifications, so I rather ask before ordering :) I would be very happy for any information, please don't just write the motor's shaft must match the wheel, I realise that :D

Shafts can be plain, with a flat, with a keyway or splined (less common).

Typically you would need to drill out a wheel to fit you shaft if too narrow, or machine an
adaptor if too small. If you can find the right diameter hub already with grub-screw that’s
going to make things easier. Grinding a flat onto a plain shaft isn’t too difficult.