Chemistry Final Exam

Four friends were taking Chemistry at the University of
Alabama. They did pretty well on all of the quizzes and the midterms
and labs, such that going into the final they had a solid "A". These
four guys were so confident going into the final that the weekend
before finals week (even though the Chemistry final was on Monday),
they decided to go up to the University of Tennessee and party with
some friends. They had a great time. However, with hangovers and
everything, they overslept all day Sunday and didn't make it back to
Alabama until early Monday morning.

Rather than taking the final then, they found their professor after
the final to explain to him why they missed the exam. They told him
that they went up to the University of Tennessee for the weekend, and
had planned to come back in time to study, but that they had a flat
tire on the way back, and didn't have a spare, and couldn't get help
for a long time, so they were late in getting back to campus.

The professor thought this over and told them they could make up the
final on the following day. The guys were elated and relieved. They
studied that night and went in the next day for the final.

The professor placed them in separate rooms, and handed each of them
a test booklet and told them to begin. They looked at the first
problem, which was worth 5 Points. It was something simple about
Molarity & Solutions.

"Cool," they thought. "This is going to be easy." They did that
problem and then turned the page.

They were not prepared, however, for what they saw on this page.
It said: (95 Points)- Which tire ??