So...MC owns his own tire machine?
Putting tires on new rims at home is a serious PITA if you don't have access to one.
I mean...it's not like changing out windshield wipers or 'installing' that new $10 air freshner you bought from the gas station.
If it said that MC had waited at the place he bought the rims and THEY put them on, now that's more believable.
I'm only saying this because I slung tires for a while, many moons ago.
I realize this game takes a few *cough* liberties with reality.
p.s. The town's name is Gilford, a region or division of Los Angeles.