Newbie.......... Tyre & Wheel Sets

[GE90]

Hi

I have an Ansmann Mad Monkey, with X2C upgrade parts. Being a complete newbie, I only run the car at the local recreation ground, using cones either in the tennis courts, car park or grass. I've killed the standard kit tyres, and learnt that I need to get some seperate grass and Tarmac tyres.

Any ideas? Only looking for cheap ones, wheel and tyre sets if possible. Think I need 12mm hex.....

Thanks very much.