I am guessing 8-10 slices per pizza and since you are having fruit, chips and wings I would estimate and little less then 2 slices per adult so maybe 6-8 pizzas?
I've found that for parties with a lot of people, it's best to have them cut the pizzas into squares instead of slices--it stretches further. You could probably get away with 5 that way.
I would figure 3 pieces per person (because the guys will prob have more and the kids will have less) However, my dd will eat 2-3 slices herself at 2 years old! Then I would buy 2 trays more. You can always freeze them and have them for leftovers later! I would def do a salad also.
We had about 30-40 people at DS's birthday party and had 10 large pizzas. I think we ended up with a few extra pieces left, so it was the perfect amount.
Re: How many pizzas for 30-40 people?
Um, a lot!
I guess figure 3 pieces per person (fewer for kids, I suppose), and plan for leftovers.
I would definitely make a big, simple salad, too.
We had about 30-40 people at DS's birthday party and had 10 large pizzas. I think we ended up with a few extra pieces left, so it was the perfect amount.