changing wheel studs

Its a 1991 Cadillac Eldorado with about 170k miles. No problems before this here is the story.

My brother-in-law just had his tires replaced and about 3 days later his front drivers side tire fell off on the freeway luckily he noticed a weird sound and pulled over right when he pulled over his tire fell off. When we towed it back to the shop that did the tire change they showed us how his wheel studs were worn, stripped, and rusty. Thus it wasn't their fault so we wasted $120 in towing.

Now its sitting in front of his house and I'm driving out there to help him change the studs. One problem I can't bring all my tools because I'll be taking my bike and its about a 2hr ride. I can only bring what he needs and he has no idea what size the bolts are to take off his rotor and such. Can anyone tell me what size bolts are on this car.

Please and Thank You
-Drew