Stepchild wants wife to cosign on a vehicle

So my 20 yr old stepchild wants my wife to cosign for a newish truck. He already has the family minivan that runs fine but needs new tires. He doesn't have much saved up and is planning to leave the house soon to rent from a buddy in town. He is only making 10 per hour in a construction job that he's been doing for over a year. Wife said he should wait until he sees what his expenses are in the rental life first before taking on a regular monthly payment. Highschool diploma only. Told him to pursue a better paying job but he's reluctant. He works so intermittently it's almost like a part time job when viewing it over the whole year. He's pissed that he needs a vehicle. My guess is he's looking in the 10000 and up range. We gave him the family minivan once we bought a new used family suv. His other older brother got the equilivant 1000 to put towards a new/used vehicle. Seems pretty obvious it's a bad idea but my wife is upset that he's upset. I just think he's unrealistic and acting like a spoiled brat. He skipped dinner and locked his room door. Won't even discuss it rationally. What do you think? via /r/Parenting https://ift.tt/2Bpz1XS