Which tire ?

Two guys were taking Chemistry at the University of Mississippi. 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 two friends 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 Mississippi 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 final.

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 two 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?