Guenther (P) was a mechanic was employed by Sears when he was putting four summer tires in a car when one of the tires exploded. The tire was examined by P and D's experts. It was admitted by D that the tire in question was D's. P attempted to call his expert at trial and D objected to the offer of proof supplied. The trial court sustained that objection. P then testified, and there was a discrepancy in his testimony as to the fact that he claimed he installed a black wall and the tire that was brought out for inspections was a white wall and two inches smaller than claimed by P in his own trial testimony. P wanted to bring his expert out again, and the issue was how was that expert going to identify the tire other than by the testimony of Small, the Service Manager for Sears and the person who had the tire when both experts examined it. D objected to the introduction of the expert as he was unable to identify the tire. The trial judge sustained that objection and then directed a verdict for D. P appealed.