How do I know which tires go on the front?

I am changing back to summer tires, and just realized there are two different types of tires by two different manufacturers. One pair is slightly wider, with wider treads, the other pair is slightly thinner with more treading but the gaps between the treads are smaller. Which pair goes on the front and which on the back? Or should I just let the mechanics figure it out when i go for a wheel alignment (will it cost extra?)How do I know which tires go on the front?
Put the widest ones on the back. You don't need a mechanic. Take a floor jack and do it yourself.How do I know which tires go on the front?
dear clueless

1 let mechanic figure it

2 would help to know what car it isHow do I know which tires go on the front?
Wider on the rear

professor layton