I need offset on a 22inch Helo Cash

Ive got a friend that has 22x9.5 Helo Cash wheels with a 5x120 bolt pattern and i cant find the damn offset anywhere online or on the wheel. So i was just wondering if anyone had a set for an S-10 that knows what the offset is because wheel shops cant even tell me what the offset is because the rims are to old, and we need to know to compare for plus sizing. Thanks