need tire info on ATV

hey yall.. i just bought my mom a 4-wheeler and it needs new tires..it will not be raced at all.. i was thinkin of goin bigger cuz i think them tire are to small for it..it has on it rite now 21-7x10's and i was thinkin od either goin to 22 or 23 in tall tires...o the soil is kinda hard but will be rode in mud alot (bye me since i cant get a dirt bike for a while) and i was thinkin of the Dirt Devil A/T's for the rear..any help yall give me wil be mutch apreciaded(sp).. o yeah the wheeler is a 1988 Suzuki Quad runner 230.. i need new tire cuz they are the stock ones that came with it when it was new!

stock size is usually best when buying a tire. i suggest all-traks by maxxis for the rear and bandits up front. my all traks ripped in the soft stuff but held up great in the rocks too. best all around tire out there IMO. they last a while too. and although ive never owned bandits, i have riddin machines with them and they feel great. hook up so nicely. good luck man