40,000
If you purchase the tire(s) at the same place you mount & balance them, it should be no more than $10 per tire (I even remember Costco charging $5 a few months ago). However, if you go to a gas station or independent auto repair facility it can cost up to $20 per tire. If you pay more than $20 per tire, you've paid too much.
average pay for diesel mechanic is 40,000 in a reputable comany
Costco starts out each employee at $11.50 a hour. Most of the employees will top out at $21.00 per hour.
Forklift drivers make the same as cashiers.
it should be around $1800 -$2500 a good mechanic
People do not pay much attention to the spare tire.
About 15 dollars a hour
They don't. Costco hires out third party trucking companies to move their goods. Swift Transportation is one of the primary contractors for them.
Since it's probably a two dollar problem, it shouldn't be an issue. If it is, it would come down to whether the mechanic was careless or there was something wrong with the lug.
7-10 bucks
a class A mechanic can make 60,000 a year