If he's riding the bike on the road, then get road tires. The Continental GP Four Seasons are a good all-year tire - about $35 each. 700x32c will fit the "29er" rims. Keep in mind, if you go from a 2.2" off-road tire to a 32c road tire you will need different tubes. Also, the 2.2 probably has a Schrader valve whereas most tubes for 32c will have Presta valves. However, Continental does make a long-stem road tube with a Schrader valve.